// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// See http://dev.chromium.org/developers/design-documents/multi-process-resource-loading

#include "content/browser/loader/resource_dispatcher_host_impl.h"

#include <stddef.h>

#include <algorithm>
#include <memory>
#include <set>
#include <utility>
#include <vector>

#include "base/bind.h"
#include "base/bind_helpers.h"
#include "base/command_line.h"
#include "base/compiler_specific.h"
#include "base/debug/alias.h"
#include "base/feature_list.h"
#include "base/logging.h"
#include "base/macros.h"
#include "base/memory/ptr_util.h"
#include "base/memory/shared_memory.h"
#include "base/message_loop/message_loop.h"
#include "base/metrics/field_trial.h"
#include "base/metrics/field_trial_params.h"
#include "base/metrics/histogram_macros.h"
#include "base/metrics/sparse_histogram.h"
#include "base/stl_util.h"
#include "base/strings/string_util.h"
#include "base/task_scheduler/post_task.h"
#include "base/task_scheduler/task_traits.h"
#include "base/third_party/dynamic_annotations/dynamic_annotations.h"
#include "base/threading/thread_task_runner_handle.h"
#include "base/timer/timer.h"
#include "content/browser/appcache/appcache_interceptor.h"
#include "content/browser/appcache/appcache_navigation_handle_core.h"
#include "content/browser/appcache/chrome_appcache_service.h"
#include "content/browser/bad_message.h"
#include "content/browser/browsing_data/clear_site_data_throttle.h"
#include "content/browser/child_process_security_policy_impl.h"
#include "content/browser/frame_host/navigation_request_info.h"
#include "content/browser/loader/async_resource_handler.h"
#include "content/browser/loader/detachable_resource_handler.h"
#include "content/browser/loader/intercepting_resource_handler.h"
#include "content/browser/loader/loader_delegate.h"
#include "content/browser/loader/mime_sniffing_resource_handler.h"
#include "content/browser/loader/mojo_async_resource_handler.h"
#include "content/browser/loader/navigation_resource_handler.h"
#include "content/browser/loader/navigation_resource_throttle.h"
#include "content/browser/loader/navigation_url_loader_impl_core.h"
#include "content/browser/loader/null_resource_controller.h"
#include "content/browser/loader/redirect_to_file_resource_handler.h"
#include "content/browser/loader/resource_loader.h"
#include "content/browser/loader/resource_message_filter.h"
#include "content/browser/loader/resource_request_info_impl.h"
#include "content/browser/loader/resource_requester_info.h"
#include "content/browser/loader/resource_scheduler.h"
#include "content/browser/loader/stream_resource_handler.h"
#include "content/browser/loader/sync_resource_handler.h"
#include "content/browser/loader/throttling_resource_handler.h"
#include "content/browser/loader/upload_data_stream_builder.h"
#include "content/browser/loader/wake_lock_resource_throttle.h"
#include "content/browser/resource_context_impl.h"
#include "content/browser/service_worker/foreign_fetch_request_handler.h"
#include "content/browser/service_worker/link_header_support.h"
#include "content/browser/service_worker/service_worker_context_wrapper.h"
#include "content/browser/service_worker/service_worker_navigation_handle_core.h"
#include "content/browser/service_worker/service_worker_request_handler.h"
#include "content/browser/streams/stream.h"
#include "content/browser/streams/stream_context.h"
#include "content/browser/streams/stream_registry.h"
#include "content/common/net/url_request_service_worker_data.h"
#include "content/common/resource_messages.h"
#include "content/common/site_isolation_policy.h"
#include "content/common/view_messages.h"
#include "content/public/browser/browser_thread.h"
#include "content/public/browser/global_request_id.h"
#include "content/public/browser/navigation_ui_data.h"
#include "content/public/browser/plugin_service.h"
#include "content/public/browser/resource_dispatcher_host_delegate.h"
#include "content/public/browser/resource_request_details.h"
#include "content/public/browser/resource_throttle.h"
#include "content/public/browser/stream_handle.h"
#include "content/public/browser/stream_info.h"
#include "content/public/common/browser_side_navigation_policy.h"
#include "content/public/common/content_features.h"
#include "content/public/common/resource_request.h"
#include "content/public/common/resource_request_body.h"
#include "content/public/common/resource_request_completion_status.h"
#include "ipc/ipc_message_macros.h"
#include "ipc/ipc_message_start.h"
#include "net/base/auth.h"
#include "net/base/load_flags.h"
#include "net/base/mime_util.h"
#include "net/base/net_errors.h"
#include "net/base/registry_controlled_domains/registry_controlled_domain.h"
#include "net/base/upload_data_stream.h"
#include "net/cert/cert_status_flags.h"
#include "net/cookies/cookie_monster.h"
#include "net/http/http_request_headers.h"
#include "net/http/http_response_headers.h"
#include "net/http/http_response_info.h"
#include "net/log/net_log_with_source.h"
#include "net/ssl/client_cert_store.h"
#include "net/ssl/ssl_cert_request_info.h"
#include "net/traffic_annotation/network_traffic_annotation.h"
#include "net/url_request/url_request.h"
#include "net/url_request/url_request_context.h"
#include "net/url_request/url_request_context_getter.h"
#include "net/url_request/url_request_job_factory.h"
#include "ppapi/features/features.h"
#include "storage/browser/blob/blob_data_handle.h"
#include "storage/browser/blob/blob_storage_context.h"
#include "storage/browser/blob/blob_url_request_job_factory.h"
#include "storage/browser/blob/shareable_file_reference.h"
#include "storage/browser/fileapi/file_permission_policy.h"
#include "storage/browser/fileapi/file_system_context.h"
#include "url/third_party/mozilla/url_parse.h"
#include "url/url_constants.h"

using base::Time;
using base::TimeDelta;
using base::TimeTicks;
using storage::ShareableFileReference;
using SyncLoadResultCallback =
    content::ResourceDispatcherHostImpl::SyncLoadResultCallback;

// ----------------------------------------------------------------------------

namespace {

constexpr net::NetworkTrafficAnnotationTag kTrafficAnnotation =
    net::DefineNetworkTrafficAnnotation("resource_dispatcher_host",
                                        R"(
        semantics {
          sender: "Resource Dispatcher Host"
          description:
            "Navigation-initiated request or renderer process initiated "
            "request, which includes all resources for normal page loads, "
            "chrome URLs, resources for installed extensions, as well as "
            "downloads."
          trigger:
            "Navigating to a URL or downloading a file. A webpage, "
            "ServiceWorker, chrome:// page, or extension may also initiate "
            "requests in the background."
          data: "Anything the initiator wants to send."
          destination: OTHER
        }
        policy {
          cookies_allowed: YES
          cookies_store: "user or per-app cookie store"
          setting: "These requests cannot be disabled."
          policy_exception_justification:
            "Not implemented. Without these requests, Chrome will be unable to "
            "load any webpage."
        })");

}  // namespace

namespace content {

namespace {

static ResourceDispatcherHostImpl* g_resource_dispatcher_host;

// The interval for calls to ResourceDispatcherHostImpl::UpdateLoadStates
const int kUpdateLoadStatesIntervalMsec = 250;

// The interval for calls to RecordOutstandingRequestsStats.
const int kRecordOutstandingRequestsStatsIntervalSec = 60;

// Maximum byte "cost" of all the outstanding requests for a renderer.
// See declaration of |max_outstanding_requests_cost_per_process_| for details.
// This bound is 25MB, which allows for around 6000 outstanding requests.
const int kMaxOutstandingRequestsCostPerProcess = 26214400;

// The number of milliseconds after noting a user gesture that we will
// tag newly-created URLRequest objects with the
// net::LOAD_MAYBE_USER_GESTURE load flag. This is a fairly arbitrary
// guess at how long to expect direct impact from a user gesture, but
// this should be OK as the load flag is a best-effort thing only,
// rather than being intended as fully accurate.
const int kUserGestureWindowMs = 3500;

// Ratio of |max_num_in_flight_requests_| that any one renderer is allowed to
// use. Arbitrarily chosen.
const double kMaxRequestsPerProcessRatio = 0.45;

// TODO(jkarlin): The value is high to reduce the chance of the detachable
// request timing out, forcing a blocked second request to open a new connection
// and start over. Reduce this value once we have a better idea of what it
// should be and once we stop blocking multiple simultaneous requests for the
// same resource (see bugs 46104 and 31014).
const int kDefaultDetachableCancelDelayMs = 30000;

// Aborts a request before an URLRequest has actually been created.
void AbortRequestBeforeItStarts(
    IPC::Sender* sender,
    const SyncLoadResultCallback& sync_result_handler,
    int request_id,
    mojom::URLLoaderClientPtr url_loader_client) {
  if (sync_result_handler) {
    SyncLoadResult result;
    result.error_code = net::ERR_ABORTED;
    sync_result_handler.Run(&result);
  } else {
    // Tell the renderer that this request was disallowed.
    ResourceRequestCompletionStatus request_complete_data;
    request_complete_data.error_code = net::ERR_ABORTED;
    request_complete_data.exists_in_cache = false;
    // No security info needed, connection not established.
    request_complete_data.completion_time = base::TimeTicks();
    request_complete_data.encoded_data_length = 0;
    request_complete_data.encoded_body_length = 0;
    if (url_loader_client) {
      url_loader_client->OnComplete(request_complete_data);
    } else {
      sender->Send(
          new ResourceMsg_RequestComplete(request_id, request_complete_data));
    }
  }
}

void RemoveDownloadFileFromChildSecurityPolicy(int child_id,
                                               const base::FilePath& path) {
  ChildProcessSecurityPolicyImpl::GetInstance()->RevokeAllPermissionsForFile(
      child_id, path);
}

bool IsValidatedSCT(
    const net::SignedCertificateTimestampAndStatus& sct_status) {
  return sct_status.status == net::ct::SCT_STATUS_OK;
}

// Returns the PreviewsState after requesting it from the delegate. The
// PreviewsState is a bitmask of potentially several Previews optimizations.
// If previews_to_allow is set to anything other than PREVIEWS_UNSPECIFIED,
// it is either the values passed in for a sub-frame to use, or if this is
// the main frame, it is a limitation on which previews to allow.
PreviewsState GetPreviewsState(PreviewsState previews_to_allow,
                               ResourceDispatcherHostDelegate* delegate,
                               const net::URLRequest& request,
                               ResourceContext* resource_context,
                               bool is_main_frame) {
  // If previews have already been turned off, or we are inheriting values on a
  // sub-frame, don't check any further.
  if (previews_to_allow & PREVIEWS_OFF ||
      previews_to_allow & PREVIEWS_NO_TRANSFORM || !is_main_frame ||
      !delegate) {
    return previews_to_allow;
  }

  // Get the mask of previews we could apply to the current navigation.
  PreviewsState previews_state =
      delegate->GetPreviewsState(request, resource_context, previews_to_allow);

  return previews_state;
}

// Sends back the result of a synchronous loading result to the renderer through
// Chrome IPC.
void HandleSyncLoadResult(base::WeakPtr<ResourceMessageFilter> filter,
                          std::unique_ptr<IPC::Message> sync_result,
                          const SyncLoadResult* result) {
  if (!filter)
    return;

  if (result) {
    ResourceHostMsg_SyncLoad::WriteReplyParams(sync_result.get(), *result);
  } else {
    sync_result->set_reply_error();
  }
  filter->Send(sync_result.release());
}

// Used to log the cache flags for back-forward navigation requests.
// Because this enum is used to back a histogrma, DO NOT REMOVE OR RENAME VALUES
// in this enum. Instead, add a new one at the end.
// TODO(clamy): Remove this once we know the reason behind PlzNavigate's
// regression on PLT for back forward navigations.
enum HistogramCacheFlag {
  HISTOGRAM_VALIDATE_CACHE,
  HISTOGRAM_BYPASS_CACHE,
  HISTOGRAM_SKIP_CACHE_VALIDATION,
  HISTOGRAM_ONLY_FROM_CACHE,
  HISTOGRAM_DISABLE_CACHE,
  HISTOGRAM_CACHE_FLAG_MAX = HISTOGRAM_DISABLE_CACHE,
};

void RecordCacheFlags(HistogramCacheFlag flag) {
  UMA_HISTOGRAM_ENUMERATION("Navigation.BackForward.CacheFlags", flag,
                            HISTOGRAM_CACHE_FLAG_MAX);
}

void LogBackForwardNavigationFlagsHistogram(int load_flags) {
  if (load_flags & net::LOAD_VALIDATE_CACHE)
    RecordCacheFlags(HISTOGRAM_VALIDATE_CACHE);

  if (load_flags & net::LOAD_BYPASS_CACHE)
    RecordCacheFlags(HISTOGRAM_BYPASS_CACHE);

  if (load_flags & net::LOAD_SKIP_CACHE_VALIDATION)
    RecordCacheFlags(HISTOGRAM_SKIP_CACHE_VALIDATION);

  if (load_flags & net::LOAD_ONLY_FROM_CACHE)
    RecordCacheFlags(HISTOGRAM_ONLY_FROM_CACHE);

  if (load_flags & net::LOAD_DISABLE_CACHE)
    RecordCacheFlags(HISTOGRAM_DISABLE_CACHE);
}

}  // namespace

ResourceDispatcherHostImpl::LoadInfo::LoadInfo() {}
ResourceDispatcherHostImpl::LoadInfo::LoadInfo(const LoadInfo& other) = default;
ResourceDispatcherHostImpl::LoadInfo::~LoadInfo() {}

ResourceDispatcherHostImpl::HeaderInterceptorInfo::HeaderInterceptorInfo() {}

ResourceDispatcherHostImpl::HeaderInterceptorInfo::~HeaderInterceptorInfo() {}

ResourceDispatcherHostImpl::HeaderInterceptorInfo::HeaderInterceptorInfo(
    const HeaderInterceptorInfo& other) {}

// static
ResourceDispatcherHost* ResourceDispatcherHost::Get() {
  return g_resource_dispatcher_host;
}

ResourceDispatcherHostImpl::ResourceDispatcherHostImpl(
    CreateDownloadHandlerIntercept download_handler_intercept,
    const scoped_refptr<base::SingleThreadTaskRunner>& io_thread_runner)
    : request_id_(-1),
      is_shutdown_(false),
      num_in_flight_requests_(0),
      max_num_in_flight_requests_(base::SharedMemory::GetHandleLimit()),
      max_num_in_flight_requests_per_process_(static_cast<int>(
          max_num_in_flight_requests_ * kMaxRequestsPerProcessRatio)),
      max_outstanding_requests_cost_per_process_(
          kMaxOutstandingRequestsCostPerProcess),
      largest_outstanding_request_count_seen_(0),
      largest_outstanding_request_per_process_count_seen_(0),
      delegate_(nullptr),
      loader_delegate_(nullptr),
      allow_cross_origin_auth_prompt_(false),
      create_download_handler_intercept_(download_handler_intercept),
      main_thread_task_runner_(base::ThreadTaskRunnerHandle::Get()),
      io_thread_task_runner_(io_thread_runner) {
  DCHECK(main_thread_task_runner_->BelongsToCurrentThread());
  DCHECK(!g_resource_dispatcher_host);
  g_resource_dispatcher_host = this;

  ANNOTATE_BENIGN_RACE(
      &last_user_gesture_time_,
      "We don't care about the precise value, see http://crbug.com/92889");

  io_thread_task_runner_->PostTask(
      FROM_HERE, base::BindOnce(&ResourceDispatcherHostImpl::OnInit,
                                base::Unretained(this)));

  update_load_states_timer_ = base::MakeUnique<base::RepeatingTimer>();

  // Monitor per-tab outstanding requests only if OOPIF is not enabled, because
  // the routing id doesn't represent tabs in OOPIF modes.
  if (!SiteIsolationPolicy::UseDedicatedProcessesForAllSites() &&
      !SiteIsolationPolicy::IsTopDocumentIsolationEnabled() &&
      !SiteIsolationPolicy::AreIsolatedOriginsEnabled()) {
    record_outstanding_requests_stats_timer_ =
        base::MakeUnique<base::RepeatingTimer>();
  }
}

// The default ctor is only used by unittests. It is reasonable to assume that
// the main thread and the IO thread are the same for unittests.
ResourceDispatcherHostImpl::ResourceDispatcherHostImpl()
    : ResourceDispatcherHostImpl(CreateDownloadHandlerIntercept(),
                                 base::ThreadTaskRunnerHandle::Get()) {}

ResourceDispatcherHostImpl::~ResourceDispatcherHostImpl() {
  DCHECK(outstanding_requests_stats_map_.empty());
  DCHECK(outstanding_requests_per_tab_map_.empty());
  DCHECK(g_resource_dispatcher_host);
  DCHECK(main_thread_task_runner_->BelongsToCurrentThread());
  g_resource_dispatcher_host = NULL;
}

// static
ResourceDispatcherHostImpl* ResourceDispatcherHostImpl::Get() {
  return g_resource_dispatcher_host;
}

void ResourceDispatcherHostImpl::SetDelegate(
    ResourceDispatcherHostDelegate* delegate) {
  delegate_ = delegate;
}

void ResourceDispatcherHostImpl::SetAllowCrossOriginAuthPrompt(bool value) {
  allow_cross_origin_auth_prompt_ = value;
}

void ResourceDispatcherHostImpl::CancelRequestsForContext(
    ResourceContext* context) {
  DCHECK(io_thread_task_runner_->BelongsToCurrentThread());
  DCHECK(context);

  // Note that request cancellation has side effects. Therefore, we gather all
  // the requests to cancel first, and then we start cancelling. We assert at
  // the end that there are no more to cancel since the context is about to go
  // away.
  typedef std::vector<std::unique_ptr<ResourceLoader>> LoaderList;
  LoaderList loaders_to_cancel;

  for (LoaderMap::iterator i = pending_loaders_.begin();
       i != pending_loaders_.end();) {
    ResourceLoader* loader = i->second.get();
    if (loader->GetRequestInfo()->GetContext() == context) {
      loaders_to_cancel.push_back(std::move(i->second));
      IncrementOutstandingRequestsMemory(-1, *loader->GetRequestInfo());
      pending_loaders_.erase(i++);
    } else {
      ++i;
    }
  }

  for (BlockedLoadersMap::iterator i = blocked_loaders_map_.begin();
       i != blocked_loaders_map_.end();) {
    BlockedLoadersList* loaders = i->second.get();
    if (loaders->empty()) {
      // This can happen if BlockRequestsForRoute() has been called for a route,
      // but we haven't blocked any matching requests yet.
      ++i;
      continue;
    }
    ResourceRequestInfoImpl* info = loaders->front()->GetRequestInfo();
    if (info->GetContext() == context) {
      std::unique_ptr<BlockedLoadersList> deleter(std::move(i->second));
      blocked_loaders_map_.erase(i++);
      for (auto& loader : *loaders) {
        info = loader->GetRequestInfo();
        // We make the assumption that all requests on the list have the same
        // ResourceContext.
        DCHECK_EQ(context, info->GetContext());
        IncrementOutstandingRequestsMemory(-1, *info);
        loaders_to_cancel.push_back(std::move(loader));
      }
    } else {
      ++i;
    }
  }

#ifndef NDEBUG
  for (const auto& loader : loaders_to_cancel) {
    // There is no strict requirement that this be the case, but currently
    // downloads, streams, detachable requests, transferred requests, and
    // browser-owned requests are the only requests that aren't cancelled when
    // the associated processes go away. It may be OK for this invariant to
    // change in the future, but if this assertion fires without the invariant
    // changing, then it's indicative of a leak.
    DCHECK(
        loader->GetRequestInfo()->IsDownload() ||
        loader->GetRequestInfo()->is_stream() ||
        (loader->GetRequestInfo()->detachable_handler() &&
         loader->GetRequestInfo()->detachable_handler()->is_detached()) ||
        loader->GetRequestInfo()->requester_info()->IsBrowserSideNavigation() ||
        loader->is_transferring() ||
        loader->GetRequestInfo()->GetResourceType() ==
            RESOURCE_TYPE_SERVICE_WORKER);
  }
#endif

  loaders_to_cancel.clear();
}

void ResourceDispatcherHostImpl::ClearLoginDelegateForRequest(
    net::URLRequest* request) {
  ResourceRequestInfoImpl* info = ResourceRequestInfoImpl::ForRequest(request);
  if (info) {
    ResourceLoader* loader = GetLoader(info->GetGlobalRequestID());
    if (loader)
      loader->ClearLoginDelegate();
  }
}

void ResourceDispatcherHostImpl::RegisterInterceptor(
    const std::string& http_header,
    const std::string& starts_with,
    const InterceptorCallback& interceptor) {
  DCHECK(!http_header.empty());
  DCHECK(interceptor);
  // Only one interceptor per header is supported.
  DCHECK(http_header_interceptor_map_.find(http_header) ==
         http_header_interceptor_map_.end());

  HeaderInterceptorInfo interceptor_info;
  interceptor_info.starts_with = starts_with;
  interceptor_info.interceptor = interceptor;

  http_header_interceptor_map_[http_header] = interceptor_info;
}

void ResourceDispatcherHostImpl::ReprioritizeRequest(
    net::URLRequest* request,
    net::RequestPriority priority) {
  scheduler_->ReprioritizeRequest(request, priority);
}

void ResourceDispatcherHostImpl::Shutdown() {
  DCHECK(main_thread_task_runner_->BelongsToCurrentThread());
  io_thread_task_runner_->PostTask(
      FROM_HERE, base::BindOnce(&ResourceDispatcherHostImpl::OnShutdown,
                                base::Unretained(this)));
}

std::unique_ptr<ResourceHandler>
ResourceDispatcherHostImpl::CreateResourceHandlerForDownload(
    net::URLRequest* request,
    bool is_content_initiated,
    bool must_download,
    bool is_new_request) {
  DCHECK(!create_download_handler_intercept_.is_null());
  // TODO(ananta)
  // Find a better way to create the download handler and notifying the
  // delegate of the download start.
  std::unique_ptr<ResourceHandler> handler =
      create_download_handler_intercept_.Run(request);
  handler =
      HandleDownloadStarted(request, std::move(handler), is_content_initiated,
                            must_download, is_new_request);
  return handler;
}

std::unique_ptr<ResourceHandler>
ResourceDispatcherHostImpl::MaybeInterceptAsStream(
    const base::FilePath& plugin_path,
    net::URLRequest* request,
    ResourceResponse* response,
    std::string* payload) {
  payload->clear();
  ResourceRequestInfoImpl* info = ResourceRequestInfoImpl::ForRequest(request);
  const std::string& mime_type = response->head.mime_type;

  GURL origin;
  if (!delegate_ ||
      !delegate_->ShouldInterceptResourceAsStream(
          request, plugin_path, mime_type, &origin, payload)) {
    return std::unique_ptr<ResourceHandler>();
  }

  StreamContext* stream_context =
      GetStreamContextForResourceContext(info->GetContext());

  std::unique_ptr<StreamResourceHandler> handler(new StreamResourceHandler(
      request, stream_context->registry(), origin, false));

  info->set_is_stream(true);
  std::unique_ptr<StreamInfo> stream_info(new StreamInfo);
  stream_info->handle = handler->stream()->CreateHandle();
  stream_info->original_url = request->url();
  stream_info->mime_type = mime_type;
  // Make a copy of the response headers so it is safe to pass across threads;
  // the old handler (AsyncResourceHandler) may modify it in parallel via the
  // ResourceDispatcherHostDelegate.
  if (response->head.headers.get()) {
    stream_info->response_headers =
        new net::HttpResponseHeaders(response->head.headers->raw_headers());
  }
  delegate_->OnStreamCreated(request, std::move(stream_info));
  return std::move(handler);
}

ResourceDispatcherHostLoginDelegate*
ResourceDispatcherHostImpl::CreateLoginDelegate(
    ResourceLoader* loader,
    net::AuthChallengeInfo* auth_info) {
  if (!delegate_)
    return NULL;

  return delegate_->CreateLoginDelegate(auth_info, loader->request());
}

bool ResourceDispatcherHostImpl::HandleExternalProtocol(ResourceLoader* loader,
                                                        const GURL& url) {
  if (!delegate_)
    return false;

  ResourceRequestInfoImpl* info = loader->GetRequestInfo();

  if (!IsResourceTypeFrame(info->GetResourceType()))
    return false;

  const net::URLRequestJobFactory* job_factory =
      info->GetContext()->GetRequestContext()->job_factory();
  if (!url.is_valid() || job_factory->IsHandledProtocol(url.scheme()))
    return false;

  return delegate_->HandleExternalProtocol(url, info);
}

void ResourceDispatcherHostImpl::DidStartRequest(ResourceLoader* loader) {
  // Make sure we have the load state monitors running.
  if (!update_load_states_timer_->IsRunning() &&
      scheduler_->HasLoadingClients()) {
    update_load_states_timer_->Start(
        FROM_HERE, TimeDelta::FromMilliseconds(kUpdateLoadStatesIntervalMsec),
        this, &ResourceDispatcherHostImpl::UpdateLoadInfo);
  }
  if (record_outstanding_requests_stats_timer_ &&
      !record_outstanding_requests_stats_timer_->IsRunning()) {
    record_outstanding_requests_stats_timer_->Start(
        FROM_HERE,
        TimeDelta::FromSeconds(kRecordOutstandingRequestsStatsIntervalSec),
        this, &ResourceDispatcherHostImpl::RecordOutstandingRequestsStats);
  }
}

void ResourceDispatcherHostImpl::DidReceiveRedirect(
    ResourceLoader* loader,
    const GURL& new_url,
    ResourceResponse* response) {
  ResourceRequestInfoImpl* info = loader->GetRequestInfo();
  if (delegate_) {
    delegate_->OnRequestRedirected(
        new_url, loader->request(), info->GetContext(), response);
  }

  // Don't notify WebContents observers for requests known to be
  // downloads; they aren't really associated with the Webcontents.
  // Note that not all downloads are known before content sniffing.
  if (info->IsDownload())
    return;

  // Notify the observers on the UI thread.
  net::URLRequest* request = loader->request();
  std::unique_ptr<ResourceRedirectDetails> detail(new ResourceRedirectDetails(
      loader->request(),
      !!request->ssl_info().cert,
      new_url));
  loader_delegate_->DidGetRedirectForResourceRequest(
      info->GetWebContentsGetterForRequest(), std::move(detail));
}

void ResourceDispatcherHostImpl::DidReceiveResponse(
    ResourceLoader* loader,
    ResourceResponse* response) {
  ResourceRequestInfoImpl* info = loader->GetRequestInfo();
  net::URLRequest* request = loader->request();
  if (request->was_fetched_via_proxy() &&
      request->was_fetched_via_spdy() &&
      request->url().SchemeIs(url::kHttpScheme)) {
    scheduler_->OnReceivedSpdyProxiedHttpResponse(
        info->GetChildID(), info->GetRouteID());
  }

  ProcessRequestForLinkHeaders(request);

  if (delegate_)
    delegate_->OnResponseStarted(request, info->GetContext(), response);

  // Don't notify WebContents observers for requests known to be
  // downloads; they aren't really associated with the Webcontents.
  // Note that not all downloads are known before content sniffing.
  if (info->IsDownload())
    return;

  // Notify the observers on the UI thread.
  std::unique_ptr<ResourceRequestDetails> detail(new ResourceRequestDetails(
      request, !!request->ssl_info().cert));
  loader_delegate_->DidGetResourceResponseStart(
      info->GetWebContentsGetterForRequest(), std::move(detail));
}

void ResourceDispatcherHostImpl::DidFinishLoading(ResourceLoader* loader) {
  ResourceRequestInfoImpl* info = loader->GetRequestInfo();

  // Record final result of all resource loads.
  if (info->GetResourceType() == RESOURCE_TYPE_MAIN_FRAME) {
    // This enumeration has "3" appended to its name to distinguish it from
    // older versions.
    UMA_HISTOGRAM_SPARSE_SLOWLY(
        "Net.ErrorCodesForMainFrame3",
        -loader->request()->status().error());
    if (loader->request()->status().error() == net::ERR_ABORTED) {
      UMA_HISTOGRAM_CUSTOM_COUNTS("Net.ErrAborted.SentBytes",
                                  loader->request()->GetTotalSentBytes(), 1,
                                  50000000, 50);
      UMA_HISTOGRAM_CUSTOM_COUNTS("Net.ErrAborted.ReceivedBytes",
                                  loader->request()->GetTotalReceivedBytes(), 1,
                                  50000000, 50);
    }

    if (loader->request()->url().SchemeIsCryptographic()) {
      if (loader->request()->url().host_piece() == "www.google.com") {
        UMA_HISTOGRAM_SPARSE_SLOWLY("Net.ErrorCodesForHTTPSGoogleMainFrame2",
                                    -loader->request()->status().error());
      }

      int num_valid_scts = std::count_if(
          loader->request()->ssl_info().signed_certificate_timestamps.begin(),
          loader->request()->ssl_info().signed_certificate_timestamps.end(),
          IsValidatedSCT);
      UMA_HISTOGRAM_COUNTS_100(
          "Net.CertificateTransparency.MainFrameValidSCTCount", num_valid_scts);
    }
  } else {
    if (info->GetResourceType() == RESOURCE_TYPE_IMAGE) {
      UMA_HISTOGRAM_SPARSE_SLOWLY(
          "Net.ErrorCodesForImages",
          -loader->request()->status().error());
    }
    // This enumeration has "2" appended to distinguish it from older versions.
    UMA_HISTOGRAM_SPARSE_SLOWLY(
        "Net.ErrorCodesForSubresources2",
        -loader->request()->status().error());
  }

  if (delegate_)
    delegate_->RequestComplete(loader->request());

  // Destroy the ResourceLoader.
  RemovePendingRequest(info->GetChildID(), info->GetRequestID());
}

std::unique_ptr<net::ClientCertStore>
    ResourceDispatcherHostImpl::CreateClientCertStore(ResourceLoader* loader) {
  return delegate_->CreateClientCertStore(
      loader->GetRequestInfo()->GetContext());
}

void ResourceDispatcherHostImpl::OnInit() {
  scheduler_.reset(new ResourceScheduler);
}

void ResourceDispatcherHostImpl::OnShutdown() {
  DCHECK(io_thread_task_runner_->BelongsToCurrentThread());

  is_shutdown_ = true;
  pending_loaders_.clear();

  // Make sure we shutdown the timers now, otherwise by the time our destructor
  // runs if the timer is still running the Task is deleted twice (once by
  // the MessageLoop and the second time by RepeatingTimer).
  update_load_states_timer_.reset();
  record_outstanding_requests_stats_timer_.reset();

  // Clear blocked requests if any left.
  // Note that we have to do this in 2 passes as we cannot call
  // CancelBlockedRequestsForRoute while iterating over
  // blocked_loaders_map_, as it modifies it.
  std::set<GlobalFrameRoutingId> ids;
  for (const auto& blocked_loaders : blocked_loaders_map_) {
    std::pair<std::set<GlobalFrameRoutingId>::iterator, bool> result =
        ids.insert(blocked_loaders.first);
    // We should not have duplicates.
    DCHECK(result.second);
  }
  for (const auto& routing_id : ids) {
    CancelBlockedRequestsForRoute(routing_id);
  }

  scheduler_.reset();
}

bool ResourceDispatcherHostImpl::OnMessageReceived(
    const IPC::Message& message,
    ResourceRequesterInfo* requester_info) {
  DCHECK(io_thread_task_runner_->BelongsToCurrentThread());

  bool handled = true;
  IPC_BEGIN_MESSAGE_MAP_WITH_PARAM(ResourceDispatcherHostImpl, message,
                                   requester_info)
    IPC_MESSAGE_HANDLER(ResourceHostMsg_RequestResource, OnRequestResource)
    IPC_MESSAGE_HANDLER_WITH_PARAM_DELAY_REPLY(ResourceHostMsg_SyncLoad,
                                               OnSyncLoad)
    IPC_MESSAGE_HANDLER(ResourceHostMsg_ReleaseDownloadedFile,
                        OnReleaseDownloadedFile)
    IPC_MESSAGE_HANDLER(ResourceHostMsg_CancelRequest, OnCancelRequest)
    IPC_MESSAGE_HANDLER(ResourceHostMsg_DidChangePriority, OnDidChangePriority)
    IPC_MESSAGE_UNHANDLED(handled = false)
  IPC_END_MESSAGE_MAP()

  if (!handled && IPC_MESSAGE_ID_CLASS(message.type()) == ResourceMsgStart) {
    base::PickleIterator iter(message);
    int request_id = -1;
    bool ok = iter.ReadInt(&request_id);
    DCHECK(ok);
    GlobalRequestID id(requester_info->child_id(), request_id);
    DelegateMap::iterator it = delegate_map_.find(id);
    if (it != delegate_map_.end()) {
      for (auto& delegate : *it->second) {
        if (delegate.OnMessageReceived(message)) {
          handled = true;
          break;
        }
      }
    }

    // As the unhandled resource message effectively has no consumer, mark it as
    // handled to prevent needless propagation through the filter pipeline.
    handled = true;
  }

  return handled;
}

void ResourceDispatcherHostImpl::OnRequestResource(
    ResourceRequesterInfo* requester_info,
    int routing_id,
    int request_id,
    const ResourceRequest& request_data,
    net::MutableNetworkTrafficAnnotationTag traffic_annotation) {
  OnRequestResourceInternal(
      requester_info, routing_id, request_id, false /* is_sync_load */,
      request_data, nullptr, nullptr,
      net::NetworkTrafficAnnotationTag(traffic_annotation));
}

void ResourceDispatcherHostImpl::OnRequestResourceInternal(
    ResourceRequesterInfo* requester_info,
    int routing_id,
    int request_id,
    bool is_sync_load,
    const ResourceRequest& request_data,
    mojom::URLLoaderRequest mojo_request,
    mojom::URLLoaderClientPtr url_loader_client,
    const net::NetworkTrafficAnnotationTag& traffic_annotation) {
  DCHECK(requester_info->IsRenderer() || requester_info->IsNavigationPreload());
  // When logging time-to-network only care about main frame and non-transfer
  // navigations.
  // PlzNavigate: this log happens from NavigationRequest::OnRequestStarted
  // instead.
  if (request_data.resource_type == RESOURCE_TYPE_MAIN_FRAME &&
      request_data.transferred_request_request_id == -1 &&
      !IsBrowserSideNavigationEnabled() && loader_delegate_) {
    loader_delegate_->LogResourceRequestTime(TimeTicks::Now(),
                                             requester_info->child_id(),
                                             request_data.render_frame_id,
                                             request_data.url);
  }
  BeginRequest(requester_info, request_id, request_data, is_sync_load,
               SyncLoadResultCallback(), routing_id, std::move(mojo_request),
               std::move(url_loader_client), traffic_annotation);
}

// Begins a resource request with the given params on behalf of the specified
// child process.  Responses will be dispatched through the given receiver. The
// process ID is used to lookup WebContentsImpl from routing_id's in the case of
// a request from a renderer.  request_context is the cookie/cache context to be
// used for this request.
//
// If sync_result is non-null, then a SyncLoad reply will be generated, else
// a normal asynchronous set of response messages will be generated.
void ResourceDispatcherHostImpl::OnSyncLoad(
    ResourceRequesterInfo* requester_info,
    int request_id,
    const ResourceRequest& request_data,
    IPC::Message* sync_result) {
  SyncLoadResultCallback callback =
      base::Bind(&HandleSyncLoadResult, requester_info->filter()->GetWeakPtr(),
                 base::Passed(WrapUnique(sync_result)));
  BeginRequest(requester_info, request_id, request_data,
               true /* is_sync_load */, callback, sync_result->routing_id(),
               nullptr, nullptr, kTrafficAnnotation);
}

bool ResourceDispatcherHostImpl::IsRequestIDInUse(
    const GlobalRequestID& id) const {
  if (pending_loaders_.find(id) != pending_loaders_.end())
    return true;
  for (const auto& blocked_loaders : blocked_loaders_map_) {
    for (const auto& loader : *blocked_loaders.second.get()) {
      ResourceRequestInfoImpl* info = loader->GetRequestInfo();
      if (info->GetGlobalRequestID() == id)
        return true;
    }
  }
  return false;
}

void ResourceDispatcherHostImpl::UpdateRequestForTransfer(
    ResourceRequesterInfo* requester_info,
    int route_id,
    int request_id,
    const ResourceRequest& request_data,
    LoaderMap::iterator iter,
    mojom::URLLoaderRequest mojo_request,
    mojom::URLLoaderClientPtr url_loader_client) {
  DCHECK(requester_info->IsRenderer());
  int child_id = requester_info->child_id();
  ResourceRequestInfoImpl* info = iter->second->GetRequestInfo();
  GlobalFrameRoutingId old_routing_id(request_data.transferred_request_child_id,
                                      info->GetRenderFrameID());
  GlobalRequestID old_request_id(request_data.transferred_request_child_id,
                                 request_data.transferred_request_request_id);
  GlobalFrameRoutingId new_routing_id(child_id, request_data.render_frame_id);
  GlobalRequestID new_request_id(child_id, request_id);

  // Clear out data that depends on |info| before updating it.
  // We always need to move the memory stats to the new process.  In contrast,
  // stats.num_requests is only tracked for some requests (those that require
  // file descriptors for their shared memory buffer).
  IncrementOutstandingRequestsMemory(-1, *info);
  bool should_update_count = info->counted_as_in_flight_request();
  if (should_update_count)
    IncrementOutstandingRequestsCount(-1, info);

  DCHECK(pending_loaders_.find(old_request_id) == iter);
  std::unique_ptr<ResourceLoader> loader = std::move(iter->second);
  ResourceLoader* loader_ptr = loader.get();
  pending_loaders_.erase(iter);

  // ResourceHandlers should always get state related to the request from the
  // ResourceRequestInfo rather than caching it locally.  This lets us update
  // the info object when a transfer occurs.
  info->UpdateForTransfer(route_id, request_data.render_frame_id,
                          request_data.origin_pid, request_id, requester_info,
                          std::move(mojo_request),
                          std::move(url_loader_client));

  // Update maps that used the old IDs, if necessary.  Some transfers in tests
  // do not actually use a different ID, so not all maps need to be updated.
  pending_loaders_[new_request_id] = std::move(loader);
  IncrementOutstandingRequestsMemory(1, *info);
  if (should_update_count)
    IncrementOutstandingRequestsCount(1, info);
  if (old_routing_id != new_routing_id) {
    if (blocked_loaders_map_.find(old_routing_id) !=
            blocked_loaders_map_.end()) {
      blocked_loaders_map_[new_routing_id] =
          std::move(blocked_loaders_map_[old_routing_id]);
      blocked_loaders_map_.erase(old_routing_id);
    }
  }
  if (old_request_id != new_request_id) {
    DelegateMap::iterator it = delegate_map_.find(old_request_id);
    if (it != delegate_map_.end()) {
      // Tell each delegate that the request ID has changed.
      for (auto& delegate : *it->second)
        delegate.set_request_id(new_request_id);
      // Now store the observer list under the new request ID.
      delegate_map_[new_request_id] = delegate_map_[old_request_id];
      delegate_map_.erase(old_request_id);
    }
  }

  AppCacheInterceptor::CompleteCrossSiteTransfer(
      loader_ptr->request(), child_id, request_data.appcache_host_id,
      requester_info);

  ServiceWorkerRequestHandler* handler =
      ServiceWorkerRequestHandler::GetHandler(loader_ptr->request());
  if (handler) {
    if (!handler->SanityCheckIsSameContext(
            requester_info->service_worker_context())) {
      bad_message::ReceivedBadMessage(
          requester_info->filter(), bad_message::RDHI_WRONG_STORAGE_PARTITION);
    } else {
      handler->CompleteCrossSiteTransfer(
          child_id, request_data.service_worker_provider_id);
    }
  }
}

void ResourceDispatcherHostImpl::CompleteTransfer(
    ResourceRequesterInfo* requester_info,
    int request_id,
    const ResourceRequest& request_data,
    int route_id,
    mojom::URLLoaderRequest mojo_request,
    mojom::URLLoaderClientPtr url_loader_client) {
  DCHECK(requester_info->IsRenderer());
  // Caller should ensure that |request_data| is associated with a transfer.
  DCHECK(request_data.transferred_request_child_id != -1 ||
         request_data.transferred_request_request_id != -1);

  if (!IsResourceTypeFrame(request_data.resource_type)) {
    // Transfers apply only to navigational requests - the renderer seems to
    // have sent bogus IPC data.
    bad_message::ReceivedBadMessage(
        requester_info->filter(),
        bad_message::RDH_TRANSFERRING_NONNAVIGATIONAL_REQUEST);
    return;
  }

  // Attempt to find a loader associated with the deferred transfer request.
  LoaderMap::iterator it = pending_loaders_.find(
      GlobalRequestID(request_data.transferred_request_child_id,
                      request_data.transferred_request_request_id));
  if (it == pending_loaders_.end()) {
    // Renderer sent transferred_request_request_id and/or
    // transferred_request_child_id that doesn't have a corresponding entry on
    // the browser side.
    // TODO(lukasza): https://crbug.com/659613: Need to understand the scenario
    // that can lead here (and then attempt to reintroduce a renderer kill
    // below).
    return;
  }
  ResourceLoader* pending_loader = it->second.get();

  if (!pending_loader->is_transferring()) {
    // Renderer sent transferred_request_request_id and/or
    // transferred_request_child_id that doesn't correspond to an actually
    // transferring loader on the browser side.
    base::debug::Alias(pending_loader);
    bad_message::ReceivedBadMessage(requester_info->filter(),
                                    bad_message::RDH_REQUEST_NOT_TRANSFERRING);
    return;
  }

  // If the request is transferring to a new process, we can update our
  // state and let it resume with its existing ResourceHandlers.
  UpdateRequestForTransfer(requester_info, route_id, request_id, request_data,
                           it, std::move(mojo_request),
                           std::move(url_loader_client));
  pending_loader->CompleteTransfer();
}

void ResourceDispatcherHostImpl::BeginRequest(
    ResourceRequesterInfo* requester_info,
    int request_id,
    const ResourceRequest& request_data,
    bool is_sync_load,
    const SyncLoadResultCallback& sync_result_handler,  // only valid for sync
    int route_id,
    mojom::URLLoaderRequest mojo_request,
    mojom::URLLoaderClientPtr url_loader_client,
    const net::NetworkTrafficAnnotationTag& traffic_annotation) {
  DCHECK(requester_info->IsRenderer() || requester_info->IsNavigationPreload());
  int child_id = requester_info->child_id();

  // Reject request id that's currently in use.
  if (IsRequestIDInUse(GlobalRequestID(child_id, request_id))) {
    // Navigation preload requests have child_id's of -1 and monotonically
    // increasing request IDs allocated by MakeRequestID.
    DCHECK(requester_info->IsRenderer());
    bad_message::ReceivedBadMessage(requester_info->filter(),
                                    bad_message::RDH_INVALID_REQUEST_ID);
    return;
  }

  // PlzNavigate: reject invalid renderer main resource request.
  bool is_navigation_stream_request =
      IsBrowserSideNavigationEnabled() &&
      IsResourceTypeFrame(request_data.resource_type);
  if (is_navigation_stream_request &&
      !request_data.resource_body_stream_url.SchemeIs(url::kBlobScheme)) {
    // The resource_type of navigation preload requests must be SUB_RESOURCE.
    DCHECK(requester_info->IsRenderer());
    bad_message::ReceivedBadMessage(requester_info->filter(),
                                    bad_message::RDH_INVALID_URL);
    return;
  }

  // Reject invalid priority.
  if (request_data.priority < net::MINIMUM_PRIORITY ||
      request_data.priority > net::MAXIMUM_PRIORITY) {
    // The priority of navigation preload requests are copied from the original
    // request priority which must be checked beforehand.
    DCHECK(requester_info->IsRenderer());
    bad_message::ReceivedBadMessage(requester_info->filter(),
                                    bad_message::RDH_INVALID_PRIORITY);
    return;
  }

  // If we crash here, figure out what URL the renderer was requesting.
  // http://crbug.com/91398
  char url_buf[128];
  base::strlcpy(url_buf, request_data.url.spec().c_str(), arraysize(url_buf));
  base::debug::Alias(url_buf);

  // If the request that's coming in is being transferred from another process,
  // we want to reuse and resume the old loader rather than start a new one.
  if (request_data.transferred_request_child_id != -1 ||
      request_data.transferred_request_request_id != -1) {
    CompleteTransfer(requester_info, request_id, request_data, route_id,
                     std::move(mojo_request), std::move(url_loader_client));
    return;
  }

  ResourceContext* resource_context = NULL;
  net::URLRequestContext* request_context = NULL;
  requester_info->GetContexts(request_data.resource_type, &resource_context,
                              &request_context);

  // Parse the headers before calling ShouldServiceRequest, so that they are
  // available to be validated.
  if (is_shutdown_ ||
      !ShouldServiceRequest(child_id, request_data, request_data.headers,
                            requester_info, resource_context)) {
    AbortRequestBeforeItStarts(requester_info->filter(), sync_result_handler,
                               request_id, std::move(url_loader_client));
    return;
  }

  BlobHandles blob_handles;
  if (!is_navigation_stream_request) {
    storage::BlobStorageContext* blob_context =
        GetBlobStorageContext(requester_info->blob_storage_context());
    // Resolve elements from request_body and prepare upload data.
    if (request_data.request_body.get()) {
      // |blob_context| could be null when the request is from the plugins
      // because ResourceMessageFilters created in PluginProcessHost don't have
      // the blob context.
      if (blob_context) {
        // Get BlobHandles to request_body to prevent blobs and any attached
        // shareable files from being freed until upload completion. These data
        // will be used in UploadDataStream and ServiceWorkerURLRequestJob.
        if (!GetBodyBlobDataHandles(request_data.request_body.get(),
                                    resource_context, &blob_handles)) {
          AbortRequestBeforeItStarts(requester_info->filter(),
                                     sync_result_handler, request_id,
                                     std::move(url_loader_client));
          return;
        }
      }
    }

    // Check if we have a registered interceptor for the headers passed in. If
    // yes then we need to mark the current request as pending and wait for the
    // interceptor to invoke the callback with a status code indicating whether
    // the request needs to be aborted or continued.
    for (net::HttpRequestHeaders::Iterator it(request_data.headers);
         it.GetNext();) {
      HeaderInterceptorMap::iterator index =
          http_header_interceptor_map_.find(it.name());
      if (index != http_header_interceptor_map_.end()) {
        HeaderInterceptorInfo& interceptor_info = index->second;

        bool call_interceptor = true;
        if (!interceptor_info.starts_with.empty()) {
          call_interceptor =
              base::StartsWith(it.value(), interceptor_info.starts_with,
                               base::CompareCase::INSENSITIVE_ASCII);
        }
        if (call_interceptor) {
          interceptor_info.interceptor.Run(
              it.name(), it.value(), child_id, resource_context,
              base::Bind(
                  &ResourceDispatcherHostImpl::ContinuePendingBeginRequest,
                  base::Unretained(this), make_scoped_refptr(requester_info),
                  request_id, request_data, is_sync_load, sync_result_handler,
                  route_id, request_data.headers,
                  base::Passed(std::move(mojo_request)),
                  base::Passed(std::move(url_loader_client)),
                  base::Passed(std::move(blob_handles)), traffic_annotation));
          return;
        }
      }
    }
  }
  ContinuePendingBeginRequest(requester_info, request_id, request_data,
                              is_sync_load, sync_result_handler, route_id,
                              request_data.headers, std::move(mojo_request),
                              std::move(url_loader_client),
                              std::move(blob_handles), traffic_annotation,
                              HeaderInterceptorResult::CONTINUE);
}

void ResourceDispatcherHostImpl::ContinuePendingBeginRequest(
    scoped_refptr<ResourceRequesterInfo> requester_info,
    int request_id,
    const ResourceRequest& request_data,
    bool is_sync_load,
    const SyncLoadResultCallback& sync_result_handler,  // only valid for sync
    int route_id,
    const net::HttpRequestHeaders& headers,
    mojom::URLLoaderRequest mojo_request,
    mojom::URLLoaderClientPtr url_loader_client,
    BlobHandles blob_handles,
    const net::NetworkTrafficAnnotationTag& traffic_annotation,
    HeaderInterceptorResult interceptor_result) {
  DCHECK(requester_info->IsRenderer() || requester_info->IsNavigationPreload());
  DCHECK(!sync_result_handler || is_sync_load);
  if (interceptor_result != HeaderInterceptorResult::CONTINUE) {
    if (requester_info->IsRenderer() &&
        interceptor_result == HeaderInterceptorResult::KILL) {
      // TODO(ananta): Find a way to specify the right error code here. Passing
      // in a non-content error code is not safe, but future header interceptors
      // might say to kill for reasons other than illegal origins.
      bad_message::ReceivedBadMessage(requester_info->filter(),
                                      bad_message::RDH_ILLEGAL_ORIGIN);
    }
    AbortRequestBeforeItStarts(requester_info->filter(), sync_result_handler,
                               request_id, std::move(url_loader_client));
    return;
  }
  int child_id = requester_info->child_id();
  storage::BlobStorageContext* blob_context = nullptr;
  bool allow_download = false;
  bool do_not_prompt_for_login = false;
  bool report_raw_headers = false;
  int load_flags = BuildLoadFlagsForRequest(request_data, is_sync_load);
  bool is_navigation_stream_request =
      IsBrowserSideNavigationEnabled() &&
      IsResourceTypeFrame(request_data.resource_type);

  ResourceContext* resource_context = NULL;
  net::URLRequestContext* request_context = NULL;
  requester_info->GetContexts(request_data.resource_type, &resource_context,
                              &request_context);

  // Allow the observer to block/handle the request.
  if (delegate_ && !delegate_->ShouldBeginRequest(request_data.method,
                                                  request_data.url,
                                                  request_data.resource_type,
                                                  resource_context)) {
    AbortRequestBeforeItStarts(requester_info->filter(), sync_result_handler,
                               request_id, std::move(url_loader_client));
    return;
  }

  // Construct the request.
  std::unique_ptr<net::URLRequest> new_request = request_context->CreateRequest(
      is_navigation_stream_request ? request_data.resource_body_stream_url
                                   : request_data.url,
      request_data.priority, nullptr, traffic_annotation);

  if (is_navigation_stream_request) {
    // PlzNavigate: Always set the method to GET when gaining access to the
    // stream that contains the response body of a navigation. Otherwise the
    // data that was already fetched by the browser will not be transmitted to
    // the renderer.
    new_request->set_method("GET");
  } else {
    // Log that this request is a service worker navigation preload request
    // here, since navigation preload machinery has no access to netlog.
    // TODO(falken): Figure out how mojom::URLLoaderClient can
    // access the request's netlog.
    if (requester_info->IsNavigationPreload()) {
      new_request->net_log().AddEvent(
          net::NetLogEventType::SERVICE_WORKER_NAVIGATION_PRELOAD_REQUEST);
    }

    new_request->set_method(request_data.method);

    new_request->set_site_for_cookies(request_data.site_for_cookies);

    // The initiator should normally be present, unless this is a navigation in
    // a top-level frame. It may be null for some top-level navigations (eg:
    // browser-initiated ones).
    DCHECK(request_data.request_initiator.has_value() ||
           request_data.resource_type == RESOURCE_TYPE_MAIN_FRAME);
    new_request->set_initiator(request_data.request_initiator);

    if (request_data.originated_from_service_worker) {
      new_request->SetUserData(URLRequestServiceWorkerData::kUserDataKey,
                               base::MakeUnique<URLRequestServiceWorkerData>());
    }

    // If the request is a MAIN_FRAME request, the first-party URL gets updated
    // on redirects.
    if (request_data.resource_type == RESOURCE_TYPE_MAIN_FRAME) {
      new_request->set_first_party_url_policy(
          net::URLRequest::UPDATE_FIRST_PARTY_URL_ON_REDIRECT);
    }

    // For PlzNavigate, this request has already been made and the referrer was
    // checked previously. So don't set the referrer for this stream request, or
    // else it will fail for SSL redirects since net/ will think the blob:https
    // for the stream is not a secure scheme (specifically, in the call to
    // ComputeReferrerForRedirect).
    const Referrer referrer(
        request_data.referrer, request_data.referrer_policy);
    Referrer::SetReferrerForRequest(new_request.get(), referrer);

    new_request->SetExtraRequestHeaders(headers);

    blob_context =
        GetBlobStorageContext(requester_info->blob_storage_context());
    // Resolve elements from request_body and prepare upload data.
    if (request_data.request_body.get()) {
      new_request->set_upload(UploadDataStreamBuilder::Build(
          request_data.request_body.get(), blob_context,
          requester_info->file_system_context(),
          base::CreateSingleThreadTaskRunnerWithTraits(
              {base::MayBlock(), base::TaskPriority::USER_VISIBLE})
              .get()));
    }

    allow_download = request_data.allow_download &&
                     IsResourceTypeFrame(request_data.resource_type);
    do_not_prompt_for_login = request_data.do_not_prompt_for_login;

    // Raw headers are sensitive, as they include Cookie/Set-Cookie, so only
    // allow requesting them if requester has ReadRawCookies permission.
    ChildProcessSecurityPolicyImpl* policy =
        ChildProcessSecurityPolicyImpl::GetInstance();
    report_raw_headers = request_data.report_raw_headers;
    if (report_raw_headers && !policy->CanReadRawCookies(child_id) &&
        !requester_info->IsNavigationPreload()) {
      // For navigation preload, the child_id is -1 so CanReadRawCookies would
      // return false. But |report_raw_headers| of the navigation preload
      // request was copied from the original request, so this check has already
      // been carried out.
      // TODO: crbug.com/523063 can we call bad_message::ReceivedBadMessage
      // here?
      VLOG(1) << "Denied unauthorized request for raw headers";
      report_raw_headers = false;
    }

    if (request_data.resource_type == RESOURCE_TYPE_PREFETCH ||
        request_data.resource_type == RESOURCE_TYPE_FAVICON) {
      do_not_prompt_for_login = true;
    }
    if (request_data.resource_type == RESOURCE_TYPE_IMAGE &&
        HTTP_AUTH_RELATION_BLOCKED_CROSS ==
            HttpAuthRelationTypeOf(request_data.url,
                                   request_data.site_for_cookies)) {
      // Prevent third-party image content from prompting for login, as this
      // is often a scam to extract credentials for another domain from the
      // user. Only block image loads, as the attack applies largely to the
      // "src" property of the <img> tag. It is common for web properties to
      // allow untrusted values for <img src>; this is considered a fair thing
      // for an HTML sanitizer to do. Conversely, any HTML sanitizer that didn't
      // filter sources for <script>, <link>, <embed>, <object>, <iframe> tags
      // would be considered vulnerable in and of itself.
      do_not_prompt_for_login = true;
      load_flags |= net::LOAD_DO_NOT_USE_EMBEDDED_IDENTITY;
    }

    // Sync loads should have maximum priority and should be the only
    // requets that have the ignore limits flag set.
    if (is_sync_load) {
      DCHECK_EQ(request_data.priority, net::MAXIMUM_PRIORITY);
      DCHECK_NE(load_flags & net::LOAD_IGNORE_LIMITS, 0);
    } else {
      DCHECK_EQ(load_flags & net::LOAD_IGNORE_LIMITS, 0);
    }
  }

  new_request->SetLoadFlags(load_flags);

  // Update the previews state, but only if this is not using PlzNavigate.
  PreviewsState previews_state = request_data.previews_state;
  if (!IsBrowserSideNavigationEnabled()) {
    previews_state = GetPreviewsState(
        request_data.previews_state, delegate_, *new_request, resource_context,
        request_data.resource_type == RESOURCE_TYPE_MAIN_FRAME);
  }

  // Make extra info and read footer (contains request ID).
  ResourceRequestInfoImpl* extra_info = new ResourceRequestInfoImpl(
      requester_info, route_id,
      -1,  // frame_tree_node_id
      request_data.origin_pid, request_id, request_data.render_frame_id,
      request_data.is_main_frame, request_data.parent_is_main_frame,
      request_data.resource_type, request_data.transition_type,
      request_data.should_replace_current_entry,
      false,  // is download
      false,  // is stream
      allow_download, request_data.has_user_gesture,
      request_data.enable_load_timing, request_data.enable_upload_progress,
      do_not_prompt_for_login, request_data.keepalive,
      request_data.referrer_policy, request_data.visibility_state,
      resource_context, report_raw_headers, !is_sync_load, previews_state,
      request_data.request_body, request_data.initiated_in_secure_context);
  extra_info->SetBlobHandles(std::move(blob_handles));

  // Request takes ownership.
  extra_info->AssociateWithRequest(new_request.get());

  if (new_request->url().SchemeIs(url::kBlobScheme)) {
    // Hang on to a reference to ensure the blob is not released prior
    // to the job being started.
    storage::BlobProtocolHandler::SetRequestedBlobDataHandle(
        new_request.get(), requester_info->blob_storage_context()
                               ->context()
                               ->GetBlobDataFromPublicURL(new_request->url()));
  }

  std::unique_ptr<ResourceHandler> handler;
  if (is_navigation_stream_request) {
    // PlzNavigate: do not add ResourceThrottles for main resource requests from
    // the renderer.  Decisions about the navigation should have been done in
    // the initial request.
    handler = CreateBaseResourceHandler(
        new_request.get(), std::move(mojo_request),
        std::move(url_loader_client), request_data.resource_type);
  } else {
    // Initialize the service worker handler for the request. We don't use
    // ServiceWorker for synchronous loads to avoid renderer deadlocks.
    const ServiceWorkerMode service_worker_mode =
        is_sync_load ? ServiceWorkerMode::NONE
                     : request_data.service_worker_mode;
    ServiceWorkerRequestHandler::InitializeHandler(
        new_request.get(), requester_info->service_worker_context(),
        blob_context, child_id, request_data.service_worker_provider_id,
        service_worker_mode != ServiceWorkerMode::ALL,
        request_data.fetch_request_mode, request_data.fetch_credentials_mode,
        request_data.fetch_redirect_mode, request_data.fetch_integrity,
        request_data.resource_type, request_data.fetch_request_context_type,
        request_data.fetch_frame_type, request_data.request_body);

    ForeignFetchRequestHandler::InitializeHandler(
        new_request.get(), requester_info->service_worker_context(),
        blob_context, child_id, request_data.service_worker_provider_id,
        service_worker_mode, request_data.fetch_request_mode,
        request_data.fetch_credentials_mode, request_data.fetch_redirect_mode,
        request_data.fetch_integrity, request_data.resource_type,
        request_data.fetch_request_context_type, request_data.fetch_frame_type,
        request_data.request_body, request_data.initiated_in_secure_context);

    // Have the appcache associate its extra info with the request.
    AppCacheInterceptor::SetExtraRequestInfo(
        new_request.get(), requester_info->appcache_service(), child_id,
        request_data.appcache_host_id, request_data.resource_type,
        request_data.should_reset_appcache);
    handler = CreateResourceHandler(
        requester_info.get(), new_request.get(), request_data,
        sync_result_handler, route_id, child_id, resource_context,
        std::move(mojo_request), std::move(url_loader_client));
  }
  if (handler)
    BeginRequestInternal(std::move(new_request), std::move(handler));
}

std::unique_ptr<ResourceHandler>
ResourceDispatcherHostImpl::CreateResourceHandler(
    ResourceRequesterInfo* requester_info,
    net::URLRequest* request,
    const ResourceRequest& request_data,
    const SyncLoadResultCallback& sync_result_handler,
    int route_id,
    int child_id,
    ResourceContext* resource_context,
    mojom::URLLoaderRequest mojo_request,
    mojom::URLLoaderClientPtr url_loader_client) {
  DCHECK(requester_info->IsRenderer() || requester_info->IsNavigationPreload());
  // Construct the IPC resource handler.
  std::unique_ptr<ResourceHandler> handler;
  if (sync_result_handler) {
    // download_to_file is not supported for synchronous requests.
    if (request_data.download_to_file) {
      DCHECK(requester_info->IsRenderer());
      bad_message::ReceivedBadMessage(requester_info->filter(),
                                      bad_message::RDH_BAD_DOWNLOAD);
      return std::unique_ptr<ResourceHandler>();
    }

    DCHECK(!mojo_request.is_pending());
    DCHECK(!url_loader_client);
    handler.reset(new SyncResourceHandler(request, sync_result_handler, this));
  } else {
    handler = CreateBaseResourceHandler(request, std::move(mojo_request),
                                        std::move(url_loader_client),
                                        request_data.resource_type);

    // The RedirectToFileResourceHandler depends on being next in the chain.
    if (request_data.download_to_file) {
      handler.reset(
          new RedirectToFileResourceHandler(std::move(handler), request));
    }
  }

  bool start_detached = request_data.download_to_network_cache_only;

  // Prefetches and <a ping> requests outlive their child process.
  if (!sync_result_handler &&
      (start_detached || request_data.resource_type == RESOURCE_TYPE_PREFETCH ||
       request_data.keepalive)) {
    auto timeout =
        base::TimeDelta::FromMilliseconds(kDefaultDetachableCancelDelayMs);
    int timeout_set_by_finch_in_sec = base::GetFieldTrialParamByFeatureAsInt(
        features::kFetchKeepaliveTimeoutSetting, "timeout_in_sec", 0);
    // Adopt only "reasonable" values.
    if (timeout_set_by_finch_in_sec > 0 &&
        timeout_set_by_finch_in_sec < 60 * 60) {
      timeout = base::TimeDelta::FromSeconds(timeout_set_by_finch_in_sec);
    }

    std::unique_ptr<DetachableResourceHandler> detachable_handler =
        base::MakeUnique<DetachableResourceHandler>(request, timeout,
                                                    std::move(handler));
    if (start_detached)
      detachable_handler->Detach();
    handler = std::move(detachable_handler);
  }

  return AddStandardHandlers(request, request_data.resource_type,
                             resource_context,
                             request_data.fetch_request_context_type,
                             request_data.fetch_mixed_content_context_type,
                             requester_info->appcache_service(), child_id,
                             route_id, std::move(handler), nullptr, nullptr);
}

std::unique_ptr<ResourceHandler>
ResourceDispatcherHostImpl::CreateBaseResourceHandler(
    net::URLRequest* request,
    mojom::URLLoaderRequest mojo_request,
    mojom::URLLoaderClientPtr url_loader_client,
    ResourceType resource_type) {
  std::unique_ptr<ResourceHandler> handler;
  if (mojo_request.is_pending()) {
    handler.reset(new MojoAsyncResourceHandler(
        request, this, std::move(mojo_request), std::move(url_loader_client),
        resource_type));
  } else {
    handler.reset(new AsyncResourceHandler(request, this));
  }
  return handler;
}

std::unique_ptr<ResourceHandler>
ResourceDispatcherHostImpl::AddStandardHandlers(
    net::URLRequest* request,
    ResourceType resource_type,
    ResourceContext* resource_context,
    RequestContextType fetch_request_context_type,
    blink::WebMixedContentContextType fetch_mixed_content_context_type,
    AppCacheService* appcache_service,
    int child_id,
    int route_id,
    std::unique_ptr<ResourceHandler> handler,
    NavigationURLLoaderImplCore* navigation_loader_core,
    std::unique_ptr<StreamHandle> stream_handle) {
  // The InterceptingResourceHandler will replace its next handler with an
  // appropriate one based on the MIME type of the response if needed. It
  // should be placed at the end of the chain, just before |handler|.
  handler.reset(new InterceptingResourceHandler(std::move(handler), request));
  InterceptingResourceHandler* intercepting_handler =
      static_cast<InterceptingResourceHandler*>(handler.get());

  std::vector<std::unique_ptr<ResourceThrottle>> throttles;

  // Add a NavigationResourceThrottle for navigations.
  // PlzNavigate: the throttle is unnecessary as communication with the UI
  // thread is handled by the NavigationResourceHandler below.
  if (!IsBrowserSideNavigationEnabled() && IsResourceTypeFrame(resource_type)) {
    throttles.push_back(base::MakeUnique<NavigationResourceThrottle>(
        request, delegate_, fetch_request_context_type,
        fetch_mixed_content_context_type));
  }

  if (delegate_) {
    delegate_->RequestBeginning(request,
                                resource_context,
                                appcache_service,
                                resource_type,
                                &throttles);
  }

  if (request->has_upload()) {
    // Request wake lock while uploading data.
    throttles.push_back(
        base::MakeUnique<WakeLockResourceThrottle>(request->url().host()));
  }

  // The Clear-Site-Data throttle.
  std::unique_ptr<ResourceThrottle> clear_site_data_throttle =
      ClearSiteDataThrottle::MaybeCreateThrottleForRequest(request);
  if (clear_site_data_throttle)
    throttles.push_back(std::move(clear_site_data_throttle));

  // TODO(ricea): Stop looking this up so much.
  ResourceRequestInfoImpl* info = ResourceRequestInfoImpl::ForRequest(request);
  throttles.push_back(scheduler_->ScheduleRequest(child_id, route_id,
                                                  info->IsAsync(), request));

  // Split the handler in two groups: the ones that need to execute
  // WillProcessResponse before mime sniffing and the others.
  std::vector<std::unique_ptr<ResourceThrottle>> pre_mime_sniffing_throttles;
  std::vector<std::unique_ptr<ResourceThrottle>> post_mime_sniffing_throttles;
  for (auto& throttle : throttles) {
    if (throttle->MustProcessResponseBeforeReadingBody()) {
      pre_mime_sniffing_throttles.push_back(std::move(throttle));
    } else {
      post_mime_sniffing_throttles.push_back(std::move(throttle));
    }
  }
  throttles.clear();

  // Add the post mime sniffing throttles.
  handler.reset(new ThrottlingResourceHandler(
      std::move(handler), request, std::move(post_mime_sniffing_throttles)));

  if (IsBrowserSideNavigationEnabled() && IsResourceTypeFrame(resource_type)) {
    DCHECK(navigation_loader_core);
    DCHECK(stream_handle);
    // PlzNavigate
    // Add a NavigationResourceHandler that will control the flow of navigation.
    handler.reset(new NavigationResourceHandler(
        request, std::move(handler), navigation_loader_core, delegate(),
        std::move(stream_handle)));
  } else {
    DCHECK(!navigation_loader_core);
    DCHECK(!stream_handle);
  }

  PluginService* plugin_service = nullptr;
#if BUILDFLAG(ENABLE_PLUGINS)
  plugin_service = PluginService::GetInstance();
#endif

  // Insert a buffered event handler to sniff the mime type.
  // Note: all ResourceHandler following the MimeSniffingResourceHandler
  // should expect OnWillRead to be called *before* OnResponseStarted as
  // part of the mime sniffing process.
  handler.reset(new MimeSniffingResourceHandler(
      std::move(handler), this, plugin_service, intercepting_handler, request,
      fetch_request_context_type));

  // Add the pre mime sniffing throttles.
  handler.reset(new ThrottlingResourceHandler(
      std::move(handler), request, std::move(pre_mime_sniffing_throttles)));

  return handler;
}

void ResourceDispatcherHostImpl::OnReleaseDownloadedFile(
    ResourceRequesterInfo* requester_info,
    int request_id) {
  UnregisterDownloadedTempFile(requester_info->child_id(), request_id);
}

void ResourceDispatcherHostImpl::OnDidChangePriority(
    ResourceRequesterInfo* requester_info,
    int request_id,
    net::RequestPriority new_priority,
    int intra_priority_value) {
  ResourceLoader* loader = GetLoader(requester_info->child_id(), request_id);
  // The request may go away before processing this message, so |loader| can
  // legitimately be null.
  if (!loader)
    return;

  scheduler_->ReprioritizeRequest(loader->request(), new_priority,
                                  intra_priority_value);
}

void ResourceDispatcherHostImpl::RegisterDownloadedTempFile(
    int child_id, int request_id, const base::FilePath& file_path) {
  scoped_refptr<ShareableFileReference> reference =
      ShareableFileReference::Get(file_path);
  DCHECK(reference.get());

  registered_temp_files_[child_id][request_id] = reference;
  ChildProcessSecurityPolicyImpl::GetInstance()->GrantReadFile(
      child_id, reference->path());

  // When the temp file is deleted, revoke permissions that the renderer has
  // to that file. This covers an edge case where the file is deleted and then
  // the same name is re-used for some other purpose, we don't want the old
  // renderer to still have access to it.
  //
  // We do this when the file is deleted because the renderer can take a blob
  // reference to the temp file that outlives the url loaded that it was
  // loaded with to keep the file (and permissions) alive.
  reference->AddFinalReleaseCallback(
      base::Bind(&RemoveDownloadFileFromChildSecurityPolicy,
                 child_id));
}

void ResourceDispatcherHostImpl::UnregisterDownloadedTempFile(
    int child_id, int request_id) {
  DeletableFilesMap& map = registered_temp_files_[child_id];
  DeletableFilesMap::iterator found = map.find(request_id);
  if (found == map.end())
    return;

  map.erase(found);

  // Note that we don't remove the security bits here. This will be done
  // when all file refs are deleted (see RegisterDownloadedTempFile).
}

bool ResourceDispatcherHostImpl::Send(IPC::Message* message) {
  delete message;
  return false;
}

void ResourceDispatcherHostImpl::OnCancelRequest(
    ResourceRequesterInfo* requester_info,
    int request_id) {
  CancelRequestFromRenderer(
      GlobalRequestID(requester_info->child_id(), request_id));
}

ResourceRequestInfoImpl* ResourceDispatcherHostImpl::CreateRequestInfo(
    int child_id,
    int render_view_route_id,
    int render_frame_route_id,
    PreviewsState previews_state,
    bool download,
    ResourceContext* context) {
  return new ResourceRequestInfoImpl(
      ResourceRequesterInfo::CreateForDownloadOrPageSave(child_id),
      render_view_route_id,
      -1,  // frame_tree_node_id
      0, MakeRequestID(), render_frame_route_id,
      false,  // is_main_frame
      false,  // parent_is_main_frame
      RESOURCE_TYPE_SUB_RESOURCE, ui::PAGE_TRANSITION_LINK,
      false,     // should_replace_current_entry
      download,  // is_download
      false,     // is_stream
      download,  // allow_download
      false,     // has_user_gesture
      false,     // enable_load_timing
      false,     // enable_upload_progress
      false,     // do_not_prompt_for_login
      false,     // keepalive
      blink::kWebReferrerPolicyDefault, blink::kWebPageVisibilityStateVisible,
      context,
      false,           // report_raw_headers
      true,            // is_async
      previews_state,  // previews_state
      nullptr,         // body
      false);          // initiated_in_secure_context
}

void ResourceDispatcherHostImpl::OnRenderViewHostCreated(
    int child_id,
    int route_id,
    net::URLRequestContextGetter* url_request_context_getter) {
  scheduler_->OnClientCreated(child_id, route_id,
                              url_request_context_getter->GetURLRequestContext()
                                  ->network_quality_estimator());
}

void ResourceDispatcherHostImpl::OnRenderViewHostDeleted(int child_id,
                                                         int route_id) {
  scheduler_->OnClientDeleted(child_id, route_id);
}

void ResourceDispatcherHostImpl::OnRenderViewHostSetIsLoading(int child_id,
                                                              int route_id,
                                                              bool is_loading) {
  scheduler_->OnLoadingStateChanged(child_id, route_id, !is_loading);
}

void ResourceDispatcherHostImpl::MarkAsTransferredNavigation(
    const GlobalRequestID& id,
    const base::Closure& on_transfer_complete_callback) {
  GetLoader(id)->MarkAsTransferring(on_transfer_complete_callback);
}

void ResourceDispatcherHostImpl::ResumeDeferredNavigation(
    const GlobalRequestID& id) {
  ResourceLoader* loader = GetLoader(id);
  // The response we were meant to resume could have already been canceled.
  if (loader)
    loader->CompleteTransfer();
}

// The object died, so cancel and detach all requests associated with it except
// for downloads and detachable resources, which belong to the browser process
// even if initiated via a renderer.
void ResourceDispatcherHostImpl::CancelRequestsForProcess(int child_id) {
  CancelRequestsForRoute(
      GlobalFrameRoutingId(child_id, MSG_ROUTING_NONE /* cancel all */));
  registered_temp_files_.erase(child_id);
}

void ResourceDispatcherHostImpl::CancelRequestsForRoute(
    const GlobalFrameRoutingId& global_routing_id) {
  // Since pending_requests_ is a map, we first build up a list of all of the
  // matching requests to be cancelled, and then we cancel them.  Since there
  // may be more than one request to cancel, we cannot simply hold onto the map
  // iterators found in the first loop.

  // Find the global ID of all matching elements.
  int child_id = global_routing_id.child_id;
  int route_id = global_routing_id.frame_routing_id;
  bool cancel_all_routes = (route_id == MSG_ROUTING_NONE);

  bool any_requests_transferring = false;
  std::vector<GlobalRequestID> matching_requests;
  for (const auto& loader : pending_loaders_) {
    if (loader.first.child_id != child_id)
      continue;

    ResourceRequestInfoImpl* info = loader.second->GetRequestInfo();

    GlobalRequestID id(child_id, loader.first.request_id);
    DCHECK(id == loader.first);
    // Don't cancel navigations that are expected to live beyond this process.
    if (IsTransferredNavigation(id))
      any_requests_transferring = true;
    if (cancel_all_routes || route_id == info->GetRenderFrameID()) {
      if (info->detachable_handler()) {
        if (base::FeatureList::IsEnabled(
                features::kKeepAliveRendererForKeepaliveRequests) &&
            info->keepalive()) {
          // If the feature is enabled, the renderer process's lifetime is
          // prolonged so there's no need to detach.
          if (cancel_all_routes) {
            // If the process is going to shut down for other reasons, we need
            // to cancel the request.
            matching_requests.push_back(id);
          }
        } else {
          // Otherwise, use DetachableResourceHandler's functionality.
          info->detachable_handler()->Detach();
        }
      } else if (!info->IsDownload() && !info->is_stream() &&
                 !IsTransferredNavigation(id)) {
        matching_requests.push_back(id);
      }
    }
  }

  // Remove matches.
  for (size_t i = 0; i < matching_requests.size(); ++i) {
    LoaderMap::iterator iter = pending_loaders_.find(matching_requests[i]);
    // Although every matching request was in pending_requests_ when we built
    // matching_requests, it is normal for a matching request to be not found
    // in pending_requests_ after we have removed some matching requests from
    // pending_requests_.  For example, deleting a net::URLRequest that has
    // exclusive (write) access to an HTTP cache entry may unblock another
    // net::URLRequest that needs exclusive access to the same cache entry, and
    // that net::URLRequest may complete and remove itself from
    // pending_requests_. So we need to check that iter is not equal to
    // pending_requests_.end().
    if (iter != pending_loaders_.end())
      RemovePendingLoader(iter);
  }

  // Don't clear the blocked loaders or offline policy maps if any of the
  // requests in route_id are being transferred to a new process, since those
  // maps will be updated with the new route_id after the transfer.  Otherwise
  // we will lose track of this info when the old route goes away, before the
  // new one is created.
  if (any_requests_transferring)
    return;

  // Now deal with blocked requests if any.
  if (!cancel_all_routes) {
    if (blocked_loaders_map_.find(global_routing_id) !=
        blocked_loaders_map_.end()) {
      CancelBlockedRequestsForRoute(global_routing_id);
    }
  } else {
    // We have to do all render frames for the process |child_id|.
    // Note that we have to do this in 2 passes as we cannot call
    // CancelBlockedRequestsForRoute while iterating over
    // blocked_loaders_map_, as blocking requests modifies the map.
    std::set<GlobalFrameRoutingId> routing_ids;
    for (const auto& blocked_loaders : blocked_loaders_map_) {
      if (blocked_loaders.first.child_id == child_id)
        routing_ids.insert(blocked_loaders.first);
    }
    for (const GlobalFrameRoutingId& route_id : routing_ids) {
      CancelBlockedRequestsForRoute(route_id);
    }
  }
}

// Cancels the request and removes it from the list.
void ResourceDispatcherHostImpl::RemovePendingRequest(int child_id,
                                                      int request_id) {
  LoaderMap::iterator i = pending_loaders_.find(
      GlobalRequestID(child_id, request_id));
  if (i == pending_loaders_.end()) {
    NOTREACHED() << "Trying to remove a request that's not here";
    return;
  }
  RemovePendingLoader(i);
}

void ResourceDispatcherHostImpl::RemovePendingLoader(
    const LoaderMap::iterator& iter) {
  ResourceRequestInfoImpl* info = iter->second->GetRequestInfo();

  // Remove the memory credit that we added when pushing the request onto
  // the pending list.
  IncrementOutstandingRequestsMemory(-1, *info);

  pending_loaders_.erase(iter);
}

void ResourceDispatcherHostImpl::CancelRequest(int child_id,
                                               int request_id) {
  ResourceLoader* loader = GetLoader(child_id, request_id);
  if (!loader) {
    // We probably want to remove this warning eventually, but I wanted to be
    // able to notice when this happens during initial development since it
    // should be rare and may indicate a bug.
    DVLOG(1) << "Canceling a request that wasn't found";
    return;
  }

  RemovePendingRequest(child_id, request_id);
}

ResourceDispatcherHostImpl::OustandingRequestsStats
ResourceDispatcherHostImpl::GetOutstandingRequestsStats(
    const ResourceRequestInfoImpl& info) {
  OutstandingRequestsStatsMap::iterator entry =
      outstanding_requests_stats_map_.find(info.GetChildID());
  OustandingRequestsStats stats = { 0, 0 };
  if (entry != outstanding_requests_stats_map_.end())
    stats = entry->second;
  return stats;
}

void ResourceDispatcherHostImpl::UpdateOutstandingRequestsStats(
    const ResourceRequestInfoImpl& info,
    const OustandingRequestsStats& stats) {
  if (stats.memory_cost == 0 && stats.num_requests == 0)
    outstanding_requests_stats_map_.erase(info.GetChildID());
  else
    outstanding_requests_stats_map_[info.GetChildID()] = stats;
}

void ResourceDispatcherHostImpl::IncrementOutstandingRequestsPerTab(
    int count,
    const ResourceRequestInfoImpl& info) {
  auto key = std::make_pair(info.GetChildID(), info.GetRouteID());
  OutstandingRequestsPerTabMap::iterator entry =
      outstanding_requests_per_tab_map_.insert(std::make_pair(key, 0)).first;
  entry->second += count;
  DCHECK_GE(entry->second, 0);
  if (entry->second == 0)
    outstanding_requests_per_tab_map_.erase(entry);
}

ResourceDispatcherHostImpl::OustandingRequestsStats
ResourceDispatcherHostImpl::IncrementOutstandingRequestsMemory(
    int count,
    const ResourceRequestInfoImpl& info) {
  DCHECK_EQ(1, abs(count));

  // Retrieve the previous value (defaulting to 0 if not found).
  OustandingRequestsStats stats = GetOutstandingRequestsStats(info);

  // Insert/update the total; delete entries when their count reaches 0.
  stats.memory_cost += count * info.memory_cost();
  DCHECK_GE(stats.memory_cost, 0);
  UpdateOutstandingRequestsStats(info, stats);

  return stats;
}

ResourceDispatcherHostImpl::OustandingRequestsStats
ResourceDispatcherHostImpl::IncrementOutstandingRequestsCount(
    int count,
    ResourceRequestInfoImpl* info) {
  DCHECK_EQ(1, abs(count));
  num_in_flight_requests_ += count;

  // Keep track of whether this request is counting toward the number of
  // in-flight requests for this process, in case we need to transfer it to
  // another process. This should be a toggle.
  DCHECK_NE(info->counted_as_in_flight_request(), count > 0);
  info->set_counted_as_in_flight_request(count > 0);

  OustandingRequestsStats stats = GetOutstandingRequestsStats(*info);
  stats.num_requests += count;
  DCHECK_GE(stats.num_requests, 0);
  UpdateOutstandingRequestsStats(*info, stats);

  IncrementOutstandingRequestsPerTab(count, *info);

  if (num_in_flight_requests_ > largest_outstanding_request_count_seen_) {
    largest_outstanding_request_count_seen_ = num_in_flight_requests_;
    UMA_HISTOGRAM_COUNTS_1M(
        "Net.ResourceDispatcherHost.OutstandingRequests.Total",
        largest_outstanding_request_count_seen_);
  }

  if (stats.num_requests >
      largest_outstanding_request_per_process_count_seen_) {
    largest_outstanding_request_per_process_count_seen_ = stats.num_requests;
    UMA_HISTOGRAM_COUNTS_1M(
        "Net.ResourceDispatcherHost.OutstandingRequests.PerProcess",
        largest_outstanding_request_per_process_count_seen_);
  }

  if (num_in_flight_requests_ > peak_outstanding_request_count_)
    peak_outstanding_request_count_ = num_in_flight_requests_;

  if (HasRequestsFromMultipleActiveTabs() &&
      num_in_flight_requests_ > peak_outstanding_request_count_multitab_) {
    peak_outstanding_request_count_multitab_ = num_in_flight_requests_;
  }

  return stats;
}

bool ResourceDispatcherHostImpl::HasSufficientResourcesForRequest(
    net::URLRequest* request) {
  ResourceRequestInfoImpl* info = ResourceRequestInfoImpl::ForRequest(request);
  OustandingRequestsStats stats = IncrementOutstandingRequestsCount(1, info);

  if (stats.num_requests > max_num_in_flight_requests_per_process_)
    return false;
  if (num_in_flight_requests_ > max_num_in_flight_requests_)
    return false;

  return true;
}

void ResourceDispatcherHostImpl::FinishedWithResourcesForRequest(
    net::URLRequest* request) {
  ResourceRequestInfoImpl* info = ResourceRequestInfoImpl::ForRequest(request);
  IncrementOutstandingRequestsCount(-1, info);
}

void ResourceDispatcherHostImpl::BeginNavigationRequest(
    ResourceContext* resource_context,
    net::URLRequestContext* request_context,
    storage::FileSystemContext* upload_file_system_context,
    const NavigationRequestInfo& info,
    std::unique_ptr<NavigationUIData> navigation_ui_data,
    NavigationURLLoaderImplCore* loader,
    ServiceWorkerNavigationHandleCore* service_worker_handle_core,
    AppCacheNavigationHandleCore* appcache_handle_core) {
  // PlzNavigate: BeginNavigationRequest currently should only be used for the
  // browser-side navigations project.
  CHECK(IsBrowserSideNavigationEnabled());

  ResourceType resource_type = info.is_main_frame ?
      RESOURCE_TYPE_MAIN_FRAME : RESOURCE_TYPE_SUB_FRAME;

  // Do not allow browser plugin guests to navigate to non-web URLs, since they
  // cannot swap processes or grant bindings. Do not check external protocols
  // here because they're checked in
  // ChromeResourceDispatcherHostDelegate::HandleExternalProtocol.
  ChildProcessSecurityPolicyImpl* policy =
      ChildProcessSecurityPolicyImpl::GetInstance();
  bool is_external_protocol =
      info.common_params.url.is_valid() &&
      !resource_context->GetRequestContext()->job_factory()->IsHandledProtocol(
          info.common_params.url.scheme());
  bool non_web_url_in_guest =
      info.is_for_guests_only &&
      !policy->IsWebSafeScheme(info.common_params.url.scheme()) &&
      !is_external_protocol;

  if (is_shutdown_ || non_web_url_in_guest ||
      (delegate_ && !delegate_->ShouldBeginRequest(
          info.common_params.method,
          info.common_params.url,
          resource_type,
          resource_context))) {
    loader->NotifyRequestFailed(false, net::ERR_ABORTED, base::nullopt, false);
    return;
  }

  int load_flags = info.begin_params.load_flags;
  load_flags |= net::LOAD_VERIFY_EV_CERT;
  if (info.is_main_frame)
    load_flags |= net::LOAD_MAIN_FRAME_DEPRECATED;

  // TODO(davidben): BuildLoadFlagsForRequest includes logic for
  // CanSendCookiesForOrigin and CanReadRawCookies. Is this needed here?

  // Sync loads should have maximum priority and should be the only
  // requests that have the ignore limits flag set.
  DCHECK(!(load_flags & net::LOAD_IGNORE_LIMITS));

  std::unique_ptr<net::URLRequest> new_request;
  new_request = request_context->CreateRequest(
      info.common_params.url, net::HIGHEST, nullptr, kTrafficAnnotation);

  new_request->set_method(info.common_params.method);
  new_request->set_site_for_cookies(info.site_for_cookies);
  new_request->set_initiator(info.begin_params.initiator_origin);
  if (info.is_main_frame) {
    new_request->set_first_party_url_policy(
        net::URLRequest::UPDATE_FIRST_PARTY_URL_ON_REDIRECT);
  }

  Referrer::SetReferrerForRequest(new_request.get(),
                                  info.common_params.referrer);

  net::HttpRequestHeaders headers;
  headers.AddHeadersFromString(info.begin_params.headers);
  new_request->SetExtraRequestHeaders(headers);

  new_request->SetLoadFlags(load_flags);

  storage::BlobStorageContext* blob_context = GetBlobStorageContext(
      GetChromeBlobStorageContextForResourceContext(resource_context));

  // Resolve elements from request_body and prepare upload data.
  ResourceRequestBody* body = info.common_params.post_data.get();
  BlobHandles blob_handles;
  if (body) {
    if (!GetBodyBlobDataHandles(body, resource_context, &blob_handles)) {
      new_request->CancelWithError(net::ERR_INSUFFICIENT_RESOURCES);
      loader->NotifyRequestFailed(false, net::ERR_ABORTED, base::nullopt,
                                  false);
      return;
    }
    new_request->set_upload(UploadDataStreamBuilder::Build(
        body, blob_context, upload_file_system_context,
        base::CreateSingleThreadTaskRunnerWithTraits(
            {base::MayBlock(), base::TaskPriority::USER_VISIBLE})
            .get()));
  }

  PreviewsState previews_state =
      GetPreviewsState(info.common_params.previews_state, delegate_,
                       *new_request, resource_context, info.is_main_frame);

  // Make extra info and read footer (contains request ID).
  //
  // TODO(davidben): Associate the request with the FrameTreeNode and/or tab so
  // that IO thread -> UI thread hops will work.
  ResourceRequestInfoImpl* extra_info = new ResourceRequestInfoImpl(
      ResourceRequesterInfo::CreateForBrowserSideNavigation(
          service_worker_handle_core
              ? service_worker_handle_core->context_wrapper()
              : scoped_refptr<ServiceWorkerContextWrapper>()),
      -1,  // route_id
      info.frame_tree_node_id,
      -1,  // request_data.origin_pid,
      MakeRequestID(),
      -1,  // request_data.render_frame_id,
      info.is_main_frame, info.parent_is_main_frame, resource_type,
      info.common_params.transition,
      // should_replace_current_entry. This was only maintained at layer for
      // request transfers and isn't needed for browser-side navigations.
      false,
      false,  // is download
      false,  // is stream
      info.common_params.allow_download, info.begin_params.has_user_gesture,
      true,   // enable_load_timing
      false,  // enable_upload_progress
      false,  // do_not_prompt_for_login
      false,  // keepalive
      info.common_params.referrer.policy, info.page_visibility_state,
      resource_context, info.report_raw_headers,
      true,  // is_async
      previews_state, info.common_params.post_data,
      // TODO(mek): Currently initiated_in_secure_context is only used for
      // subresource requests, so it doesn't matter what value it gets here.
      // If in the future this changes this should be updated to somehow get a
      // meaningful value.
      false);  // initiated_in_secure_context
  extra_info->SetBlobHandles(std::move(blob_handles));
  extra_info->set_navigation_ui_data(std::move(navigation_ui_data));

  // Request takes ownership.
  extra_info->AssociateWithRequest(new_request.get());

  if (new_request->url().SchemeIs(url::kBlobScheme)) {
    // Hang on to a reference to ensure the blob is not released prior
    // to the job being started.
    storage::BlobProtocolHandler::SetRequestedBlobDataHandle(
        new_request.get(),
        blob_context->GetBlobDataFromPublicURL(new_request->url()));
  }

  RequestContextFrameType frame_type =
      info.is_main_frame ? REQUEST_CONTEXT_FRAME_TYPE_TOP_LEVEL
                         : REQUEST_CONTEXT_FRAME_TYPE_NESTED;
  ServiceWorkerRequestHandler::InitializeForNavigation(
      new_request.get(), service_worker_handle_core, blob_context,
      info.begin_params.skip_service_worker, resource_type,
      info.begin_params.request_context_type, frame_type,
      info.are_ancestors_secure, info.common_params.post_data,
      extra_info->GetWebContentsGetterForRequest());

  // Have the appcache associate its extra info with the request.
  if (appcache_handle_core) {
    AppCacheInterceptor::SetExtraRequestInfoForHost(
        new_request.get(), appcache_handle_core->host(), resource_type, false);
  }

  StreamContext* stream_context =
      GetStreamContextForResourceContext(resource_context);
  // Note: the stream should be created with immediate mode set to true to
  // ensure that data read will be flushed to the reader as soon as it's
  // available. Otherwise, we risk delaying transmitting the body of the
  // resource to the renderer, which will delay parsing accordingly.
  std::unique_ptr<ResourceHandler> handler(
      new StreamResourceHandler(new_request.get(), stream_context->registry(),
                                new_request->url().GetOrigin(), true));
  std::unique_ptr<StreamHandle> stream_handle =
      static_cast<StreamResourceHandler*>(handler.get())
          ->stream()
          ->CreateHandle();

  // TODO(davidben): Fix the dependency on child_id/route_id. Those are used
  // by the ResourceScheduler. currently it's a no-op.
  handler = AddStandardHandlers(
      new_request.get(), resource_type, resource_context,
      info.begin_params.request_context_type,
      info.begin_params.mixed_content_context_type,
      appcache_handle_core ? appcache_handle_core->GetAppCacheService()
                           : nullptr,
      -1,  // child_id
      -1,  // route_id
      std::move(handler), loader, std::move(stream_handle));

  BeginRequestInternal(std::move(new_request), std::move(handler));
}

void ResourceDispatcherHostImpl::SetLoaderDelegate(
    LoaderDelegate* loader_delegate) {
  loader_delegate_ = loader_delegate;
}

void ResourceDispatcherHostImpl::OnRenderFrameDeleted(
    const GlobalFrameRoutingId& global_routing_id) {
  CancelRequestsForRoute(global_routing_id);
}

void ResourceDispatcherHostImpl::OnRequestResourceWithMojo(
    ResourceRequesterInfo* requester_info,
    int32_t routing_id,
    int32_t request_id,
    uint32_t options,
    const ResourceRequest& request,
    mojom::URLLoaderRequest mojo_request,
    mojom::URLLoaderClientPtr url_loader_client,
    const net::NetworkTrafficAnnotationTag& traffic_annotation) {
  DCHECK_EQ(mojom::kURLLoadOptionNone,
            options & ~mojom::kURLLoadOptionSynchronous);
  bool is_sync_load = options & mojom::kURLLoadOptionSynchronous;
  OnRequestResourceInternal(requester_info, routing_id, request_id,
                            is_sync_load, request, std::move(mojo_request),
                            std::move(url_loader_client), traffic_annotation);
}

// static
int ResourceDispatcherHostImpl::CalculateApproximateMemoryCost(
    net::URLRequest* request) {
  // The following fields should be a minor size contribution (experimentally
  // on the order of 100). However since they are variable length, it could
  // in theory be a sizeable contribution.
  int strings_cost = 0;
  for (net::HttpRequestHeaders::Iterator it(request->extra_request_headers());
       it.GetNext();) {
    strings_cost += it.name().length() + it.value().length();
  }
  strings_cost +=
      request->original_url().parsed_for_possibly_invalid_spec().Length() +
      request->referrer().size() + request->method().size();

  // Note that this expression will typically be dominated by:
  // |kAvgBytesPerOutstandingRequest|.
  return kAvgBytesPerOutstandingRequest + strings_cost;
}

void ResourceDispatcherHostImpl::BeginRequestInternal(
    std::unique_ptr<net::URLRequest> request,
    std::unique_ptr<ResourceHandler> handler) {
  DCHECK(!request->is_pending());
  ResourceRequestInfoImpl* info =
      ResourceRequestInfoImpl::ForRequest(request.get());

  // Log metrics for back-forward navigations.
  // TODO(clamy): Remove this once we understand the reason behind the
  // back-forward PLT regression with PlzNavigate
  if ((info->GetPageTransition() & ui::PAGE_TRANSITION_FORWARD_BACK) &&
      IsResourceTypeFrame(info->GetResourceType()) &&
      request->url().SchemeIsHTTPOrHTTPS()) {
    LogBackForwardNavigationFlagsHistogram(request->load_flags());
  }

  if ((TimeTicks::Now() - last_user_gesture_time_) <
      TimeDelta::FromMilliseconds(kUserGestureWindowMs)) {
    request->SetLoadFlags(request->load_flags() | net::LOAD_MAYBE_USER_GESTURE);
  }

  // Add the memory estimate that starting this request will consume.
  info->set_memory_cost(CalculateApproximateMemoryCost(request.get()));

  // If enqueing/starting this request will exceed our per-process memory
  // bound, abort it right away.
  OustandingRequestsStats stats = IncrementOutstandingRequestsMemory(1, *info);
  if (stats.memory_cost > max_outstanding_requests_cost_per_process_) {
    // We call "CancelWithError()" as a way of setting the net::URLRequest's
    // status -- it has no effect beyond this, since the request hasn't started.
    request->CancelWithError(net::ERR_INSUFFICIENT_RESOURCES);

    bool was_resumed = false;
    // TODO(mmenke): Get rid of NullResourceController and do something more
    // reasonable.
    handler->OnResponseCompleted(
        request->status(),
        base::MakeUnique<NullResourceController>(&was_resumed));
    // TODO(darin): The handler is not ready for us to kill the request. Oops!
    DCHECK(was_resumed);

    IncrementOutstandingRequestsMemory(-1, *info);

    // A ResourceHandler must not outlive its associated URLRequest.
    handler.reset();
    return;
  }

  std::unique_ptr<ResourceLoader> loader(new ResourceLoader(
      std::move(request), std::move(handler), this));

  GlobalFrameRoutingId id(info->GetChildID(), info->GetRenderFrameID());
  BlockedLoadersMap::const_iterator iter = blocked_loaders_map_.find(id);
  if (iter != blocked_loaders_map_.end()) {
    // The request should be blocked.
    iter->second->push_back(std::move(loader));
    return;
  }

  StartLoading(info, std::move(loader));
}

void ResourceDispatcherHostImpl::InitializeURLRequest(
    net::URLRequest* request,
    const Referrer& referrer,
    bool is_download,
    int render_process_host_id,
    int render_view_routing_id,
    int render_frame_routing_id,
    PreviewsState previews_state,
    ResourceContext* context) {
  DCHECK(io_thread_task_runner_->BelongsToCurrentThread());
  DCHECK(!request->is_pending());

  Referrer::SetReferrerForRequest(request, referrer);

  ResourceRequestInfoImpl* info = CreateRequestInfo(
      render_process_host_id, render_view_routing_id, render_frame_routing_id,
      previews_state, is_download, context);
  // Request takes ownership.
  info->AssociateWithRequest(request);
}

void ResourceDispatcherHostImpl::BeginURLRequest(
    std::unique_ptr<net::URLRequest> request,
    std::unique_ptr<ResourceHandler> handler,
    bool is_download,
    bool is_content_initiated,
    bool do_not_prompt_for_login,
    ResourceContext* context) {
  DCHECK(io_thread_task_runner_->BelongsToCurrentThread());
  DCHECK(!request->is_pending());

  ResourceRequestInfoImpl* info =
      ResourceRequestInfoImpl::ForRequest(request.get());
  DCHECK(info);
  info->set_do_not_prompt_for_login(do_not_prompt_for_login);

  // TODO(ananta)
  // Find a better place for notifying the delegate about the download start.
  if (is_download && delegate()) {
    // TODO(ananta)
    // Investigate whether the blob logic should apply for the SaveAs case and
    // if yes then move the code below outside the if block.
    if (request->original_url().SchemeIs(url::kBlobScheme) &&
        !storage::BlobProtocolHandler::GetRequestBlobDataHandle(
            request.get())) {
      ChromeBlobStorageContext* blob_context =
          GetChromeBlobStorageContextForResourceContext(context);
      storage::BlobProtocolHandler::SetRequestedBlobDataHandle(
          request.get(),
          blob_context->context()->GetBlobDataFromPublicURL(
              request->original_url()));
    }
    handler = HandleDownloadStarted(
        request.get(), std::move(handler), is_content_initiated,
        true /* force_download */, true /* is_new_request */);
  }
  BeginRequestInternal(std::move(request), std::move(handler));
}

int ResourceDispatcherHostImpl::MakeRequestID() {
  DCHECK(io_thread_task_runner_->BelongsToCurrentThread());
  return --request_id_;
}

void ResourceDispatcherHostImpl::CancelRequestFromRenderer(
    GlobalRequestID request_id) {
  // When the old renderer dies, it sends a message to us to cancel its
  // requests.
  if (IsTransferredNavigation(request_id))
    return;

  ResourceLoader* loader = GetLoader(request_id);

  // It is possible that the request has been completed and removed from the
  // loader queue but the client has not processed the request completed message
  // before issuing a cancel. This happens frequently for beacons which are
  // canceled in the response received handler.
  if (!loader)
    return;

  loader->CancelRequest(true);
}

void ResourceDispatcherHostImpl::StartLoading(
    ResourceRequestInfoImpl* info,
    std::unique_ptr<ResourceLoader> loader) {
  ResourceLoader* loader_ptr = loader.get();
  DCHECK(pending_loaders_[info->GetGlobalRequestID()] == nullptr);
  pending_loaders_[info->GetGlobalRequestID()] = std::move(loader);

  loader_ptr->StartRequest();
}

void ResourceDispatcherHostImpl::OnUserGesture() {
  last_user_gesture_time_ = TimeTicks::Now();
}

net::URLRequest* ResourceDispatcherHostImpl::GetURLRequest(
    const GlobalRequestID& id) {
  ResourceLoader* loader = GetLoader(id);
  if (!loader)
    return NULL;

  return loader->request();
}

// static
bool ResourceDispatcherHostImpl::LoadInfoIsMoreInteresting(const LoadInfo& a,
                                                           const LoadInfo& b) {
  // Set |*_uploading_size| to be the size of the corresponding upload body if
  // it's currently being uploaded.

  uint64_t a_uploading_size = 0;
  if (a.load_state.state == net::LOAD_STATE_SENDING_REQUEST)
    a_uploading_size = a.upload_size;

  uint64_t b_uploading_size = 0;
  if (b.load_state.state == net::LOAD_STATE_SENDING_REQUEST)
    b_uploading_size = b.upload_size;

  if (a_uploading_size != b_uploading_size)
    return a_uploading_size > b_uploading_size;

  return a.load_state.state > b.load_state.state;
}

// static
void ResourceDispatcherHostImpl::UpdateLoadStateOnUI(
    LoaderDelegate* loader_delegate, std::unique_ptr<LoadInfoList> infos) {
  DCHECK(Get()->main_thread_task_runner_->BelongsToCurrentThread());

  std::unique_ptr<LoadInfoMap> info_map =
      PickMoreInterestingLoadInfos(std::move(infos));
  for (const auto& load_info: *info_map) {
    loader_delegate->LoadStateChanged(
        load_info.first,
        load_info.second.url, load_info.second.load_state,
        load_info.second.upload_position, load_info.second.upload_size);
  }
}

// static
std::unique_ptr<ResourceDispatcherHostImpl::LoadInfoMap>
ResourceDispatcherHostImpl::PickMoreInterestingLoadInfos(
    std::unique_ptr<LoadInfoList> infos) {
  std::unique_ptr<LoadInfoMap> info_map(new LoadInfoMap);
  for (const auto& load_info : *infos) {
    WebContents* web_contents = load_info.web_contents_getter.Run();
    if (!web_contents)
      continue;

    auto existing = info_map->find(web_contents);
    if (existing == info_map->end() ||
        LoadInfoIsMoreInteresting(load_info, existing->second)) {
      (*info_map)[web_contents] = load_info;
    }
  }
  return info_map;
}

std::unique_ptr<ResourceDispatcherHostImpl::LoadInfoList>
ResourceDispatcherHostImpl::GetLoadInfoForAllRoutes() {
  std::unique_ptr<LoadInfoList> infos(new LoadInfoList);

  for (const auto& loader : pending_loaders_) {
    net::URLRequest* request = loader.second->request();
    net::UploadProgress upload_progress = request->GetUploadProgress();

    LoadInfo load_info;
    load_info.web_contents_getter =
        loader.second->GetRequestInfo()->GetWebContentsGetterForRequest();
    load_info.url = request->url();
    load_info.load_state = request->GetLoadState();
    load_info.upload_size = upload_progress.size();
    load_info.upload_position = upload_progress.position();
    infos->push_back(load_info);
  }
  return infos;
}

void ResourceDispatcherHostImpl::UpdateLoadInfo() {
  std::unique_ptr<LoadInfoList> infos(GetLoadInfoForAllRoutes());

  // Stop the timer if there are no more pending requests. Future new requests
  // will restart it as necessary.
  // Also stop the timer if there are no loading clients, to avoid waking up
  // unnecessarily when there is a long running (hanging get) request.
  if (infos->empty() || !scheduler_->HasLoadingClients()) {
    update_load_states_timer_->Stop();
    return;
  }

  // We need to be able to compare all requests to find the most important one
  // per tab. Since some requests may be navigation requests and we don't have
  // their render frame routing IDs yet (which is what we have for subresource
  // requests), we must go to the UI thread and compare the requests using their
  // WebContents.
  main_thread_task_runner_->PostTask(
      FROM_HERE, base::BindOnce(UpdateLoadStateOnUI, loader_delegate_,
                                base::Passed(&infos)));
}

void ResourceDispatcherHostImpl::RecordOutstandingRequestsStats() {
  if (peak_outstanding_request_count_ != 0) {
    UMA_HISTOGRAM_COUNTS_1M(
        "Net.ResourceDispatcherHost.PeakOutstandingRequests",
        peak_outstanding_request_count_);
    peak_outstanding_request_count_ = num_in_flight_requests_;
  }

  if (peak_outstanding_request_count_multitab_ != 0) {
    UMA_HISTOGRAM_COUNTS_1M(
        "Net.ResourceDispatcherHost.PeakOutstandingRequests.MultiTabLoading",
        peak_outstanding_request_count_multitab_);
    peak_outstanding_request_count_multitab_ =
        HasRequestsFromMultipleActiveTabs() ? num_in_flight_requests_ : 0;
  }
}

void ResourceDispatcherHostImpl::BlockRequestsForRoute(
    const GlobalFrameRoutingId& global_routing_id) {
  DCHECK(io_thread_task_runner_->BelongsToCurrentThread());
  DCHECK(blocked_loaders_map_.find(global_routing_id) ==
         blocked_loaders_map_.end())
      << "BlockRequestsForRoute called  multiple time for the same RFH";
  blocked_loaders_map_[global_routing_id] =
      base::MakeUnique<BlockedLoadersList>();
}

void ResourceDispatcherHostImpl::ResumeBlockedRequestsForRoute(
    const GlobalFrameRoutingId& global_routing_id) {
  ProcessBlockedRequestsForRoute(global_routing_id, false);
}

void ResourceDispatcherHostImpl::CancelBlockedRequestsForRoute(
    const GlobalFrameRoutingId& global_routing_id) {
  ProcessBlockedRequestsForRoute(global_routing_id, true);
}

void ResourceDispatcherHostImpl::ProcessBlockedRequestsForRoute(
    const GlobalFrameRoutingId& global_routing_id,
    bool cancel_requests) {
  BlockedLoadersMap::iterator iter =
      blocked_loaders_map_.find(global_routing_id);
  if (iter == blocked_loaders_map_.end()) {
    // It's possible to reach here if the renderer crashed while an interstitial
    // page was showing.
    return;
  }

  BlockedLoadersList* loaders = iter->second.get();
  std::unique_ptr<BlockedLoadersList> deleter(std::move(iter->second));

  // Removing the vector from the map unblocks any subsequent requests.
  blocked_loaders_map_.erase(iter);

  for (std::unique_ptr<ResourceLoader>& loader : *loaders) {
    ResourceRequestInfoImpl* info = loader->GetRequestInfo();
    if (cancel_requests) {
      IncrementOutstandingRequestsMemory(-1, *info);
    } else {
      StartLoading(info, std::move(loader));
    }
  }
}

ResourceDispatcherHostImpl::HttpAuthRelationType
ResourceDispatcherHostImpl::HttpAuthRelationTypeOf(
    const GURL& request_url,
    const GURL& first_party) {
  if (!first_party.is_valid())
    return HTTP_AUTH_RELATION_TOP;

  if (net::registry_controlled_domains::SameDomainOrHost(
          first_party, request_url,
          net::registry_controlled_domains::INCLUDE_PRIVATE_REGISTRIES))
    return HTTP_AUTH_RELATION_SAME_DOMAIN;

  if (allow_cross_origin_auth_prompt())
    return HTTP_AUTH_RELATION_ALLOWED_CROSS;

  return HTTP_AUTH_RELATION_BLOCKED_CROSS;
}

bool ResourceDispatcherHostImpl::allow_cross_origin_auth_prompt() {
  return allow_cross_origin_auth_prompt_;
}

bool ResourceDispatcherHostImpl::IsTransferredNavigation(
    const GlobalRequestID& id) const {
  ResourceLoader* loader = GetLoader(id);
  return loader ? loader->is_transferring() : false;
}

ResourceLoader* ResourceDispatcherHostImpl::GetLoader(
    const GlobalRequestID& id) const {
  DCHECK(io_thread_task_runner_->BelongsToCurrentThread());

  LoaderMap::const_iterator i = pending_loaders_.find(id);
  if (i == pending_loaders_.end())
    return NULL;

  return i->second.get();
}

ResourceLoader* ResourceDispatcherHostImpl::GetLoader(int child_id,
                                                      int request_id) const {
  return GetLoader(GlobalRequestID(child_id, request_id));
}

void ResourceDispatcherHostImpl::RegisterResourceMessageDelegate(
    const GlobalRequestID& id, ResourceMessageDelegate* delegate) {
  DelegateMap::iterator it = delegate_map_.find(id);
  if (it == delegate_map_.end()) {
    it = delegate_map_.insert(
                           std::make_pair(
                               id,
                               new base::ObserverList<ResourceMessageDelegate>))
             .first;
  }
  it->second->AddObserver(delegate);
}

void ResourceDispatcherHostImpl::UnregisterResourceMessageDelegate(
    const GlobalRequestID& id, ResourceMessageDelegate* delegate) {
  DCHECK(base::ContainsKey(delegate_map_, id));
  DelegateMap::iterator it = delegate_map_.find(id);
  DCHECK(it->second->HasObserver(delegate));
  it->second->RemoveObserver(delegate);
  if (!it->second->might_have_observers()) {
    delete it->second;
    delegate_map_.erase(it);
  }
}

int ResourceDispatcherHostImpl::BuildLoadFlagsForRequest(
    const ResourceRequest& request_data,
    bool is_sync_load) {
  int load_flags = request_data.load_flags;

  // Although EV status is irrelevant to sub-frames and sub-resources, we have
  // to perform EV certificate verification on all resources because an HTTP
  // keep-alive connection created to load a sub-frame or a sub-resource could
  // be reused to load a main frame.
  load_flags |= net::LOAD_VERIFY_EV_CERT;
  if (request_data.resource_type == RESOURCE_TYPE_MAIN_FRAME) {
    load_flags |= net::LOAD_MAIN_FRAME_DEPRECATED;
  } else if (request_data.resource_type == RESOURCE_TYPE_PREFETCH) {
    load_flags |= net::LOAD_PREFETCH;
  }

  if (is_sync_load)
    load_flags |= net::LOAD_IGNORE_LIMITS;

  return load_flags;
}

bool ResourceDispatcherHostImpl::ShouldServiceRequest(
    int child_id,
    const ResourceRequest& request_data,
    const net::HttpRequestHeaders& headers,
    ResourceRequesterInfo* requester_info,
    ResourceContext* resource_context) {
  ChildProcessSecurityPolicyImpl* policy =
      ChildProcessSecurityPolicyImpl::GetInstance();
  bool is_navigation_stream_request =
      IsBrowserSideNavigationEnabled() &&
      IsResourceTypeFrame(request_data.resource_type);
  // Check if the renderer is permitted to request the requested URL.
  // PlzNavigate: no need to check the URL here. The browser already picked the
  // right renderer to send the request to. The original URL isn't used, as the
  // renderer is fetching the stream URL. Checking the original URL doesn't work
  // in case of redirects across schemes, since the original URL might not be
  // granted to the final URL's renderer.
  if (!is_navigation_stream_request &&
      !policy->CanRequestURL(child_id, request_data.url)) {
    VLOG(1) << "Denied unauthorized request for "
            << request_data.url.possibly_invalid_spec();
    return false;
  }

  // Check if the renderer is using an illegal Origin header.  If so, kill it.
  std::string origin_string;
  bool has_origin =
      headers.GetHeader("Origin", &origin_string) && origin_string != "null";
  if (has_origin) {
    GURL origin(origin_string);
    if (!policy->CanSetAsOriginHeader(child_id, origin)) {
      VLOG(1) << "Killed renderer for illegal origin: " << origin_string;
      bad_message::ReceivedBadMessage(requester_info->filter(),
                                      bad_message::RDH_ILLEGAL_ORIGIN);
      return false;
    }
  }

  // Check if the renderer is permitted to upload the requested files.
  if (!policy->CanReadRequestBody(child_id,
                                  requester_info->file_system_context(),
                                  request_data.request_body)) {
    NOTREACHED() << "Denied unauthorized upload";
    return false;
  }

  return true;
}

std::unique_ptr<ResourceHandler>
ResourceDispatcherHostImpl::HandleDownloadStarted(
    net::URLRequest* request,
    std::unique_ptr<ResourceHandler> handler,
    bool is_content_initiated,
    bool must_download,
    bool is_new_request) {
  if (delegate()) {
    const ResourceRequestInfoImpl* request_info(
        ResourceRequestInfoImpl::ForRequest(request));
    std::vector<std::unique_ptr<ResourceThrottle>> throttles;
    delegate()->DownloadStarting(request, request_info->GetContext(),
                                 is_content_initiated, true, is_new_request,
                                 &throttles);
    if (!throttles.empty()) {
      handler.reset(new ThrottlingResourceHandler(std::move(handler), request,
                                                  std::move(throttles)));
    }
  }
  return handler;
}

bool ResourceDispatcherHostImpl::HasRequestsFromMultipleActiveTabs() {
  if (outstanding_requests_per_tab_map_.size() < 2)
    return false;

  int active_tabs = 0;
  for (auto iter = outstanding_requests_per_tab_map_.begin();
       iter != outstanding_requests_per_tab_map_.end(); ++iter) {
    if (iter->second > 2) {
      active_tabs++;
      if (active_tabs >= 2)
        return true;
    }
  }
  return false;
}

}  // namespace content