chrome/browser/renderer_host/safe_browsing_resource_throttle.cc - chromium/src - Git at Google

 // 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.

 #include "chrome/browser/renderer_host/safe_browsing_resource_throttle.h"

 #include "base/logging.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/values.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/prerender/prerender_contents.h"
 #include "chrome/browser/safe_browsing/safe_browsing_service.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/render_view_host.h"
 #include "content/public/browser/resource_controller.h"
 #include "content/public/browser/resource_request_info.h"
 #include "content/public/browser/web_contents.h"
 #include "net/base/load_flags.h"
 #include "net/log/net_log.h"
 #include "net/url_request/redirect_info.h"
 #include "net/url_request/url_request.h"

 using net::NetLog;
 using safe_browsing::SafeBrowsingUIManager;

 namespace {

 // Maximum time in milliseconds to wait for the safe browsing service to
 // verify a URL. After this amount of time the outstanding check will be
 // aborted, and the URL will be treated as if it were safe.
 const int kCheckUrlTimeoutMs = 5000;

 void RecordHistogramResourceTypeSafe(content::ResourceType resource_type) {
   UMA_HISTOGRAM_ENUMERATION("SB2.ResourceTypes2.Safe", resource_type,
                             content::RESOURCE_TYPE_LAST_TYPE);
 }

 // Return a dictionary with "url"=|url-spec| and optionally
 // |name|=|value| (if not null), for netlogging.
 // This will also add a reference to the original request's net_log ID.
 scoped_ptr<base::Value> NetLogUrlCallback(
     const net::URLRequest* request,
     const GURL& url,
     const char* name,
     const char* value,
     net::NetLogCaptureMode /* capture_mode */) {
   scoped_ptr<base::DictionaryValue> event_params(new base::DictionaryValue());
   event_params->SetString("url", url.spec());
   if (name && value)
     event_params->SetString(name, value);
   request->net_log().source().AddToEventParameters(event_params.get());
   return event_params.Pass();
 }

 // Return a dictionary with |name|=|value|, for netlogging.
 scoped_ptr<base::Value> NetLogStringCallback(
     const char* name,
     const char* value,
     net::NetLogCaptureMode) {
   scoped_ptr<base::DictionaryValue> event_params(new base::DictionaryValue());
   if (name && value)
     event_params->SetString(name, value);
   return event_params.Pass();
 }

 }  // namespace

 // TODO(eroman): Downgrade these CHECK()s to DCHECKs once there is more
 //               unit test coverage.

 // static
 SafeBrowsingResourceThrottle* SafeBrowsingResourceThrottle::MaybeCreate(
     net::URLRequest* request,
     content::ResourceType resource_type,
     safe_browsing::SafeBrowsingService* sb_service) {
   if (sb_service->database_manager()->IsSupported()) {
     return new SafeBrowsingResourceThrottle(request, resource_type, sb_service);
   }
   return nullptr;
 }

 SafeBrowsingResourceThrottle::SafeBrowsingResourceThrottle(
     const net::URLRequest* request,
     content::ResourceType resource_type,
     safe_browsing::SafeBrowsingService* sb_service)
     : state_(STATE_NONE),
       defer_state_(DEFERRED_NONE),
       threat_type_(safe_browsing::SB_THREAT_TYPE_SAFE),
       database_manager_(sb_service->database_manager()),
       ui_manager_(sb_service->ui_manager()),
       request_(request),
       resource_type_(resource_type),
       bound_net_log_(net::BoundNetLog::Make(request->net_log().net_log(),
                                             NetLog::SOURCE_SAFE_BROWSING)) {}

 SafeBrowsingResourceThrottle::~SafeBrowsingResourceThrottle() {
   if (defer_state_ != DEFERRED_NONE) {
     EndNetLogEvent(NetLog::TYPE_SAFE_BROWSING_DEFERRED, nullptr, nullptr);
   }

   if (state_ == STATE_CHECKING_URL) {
     database_manager_->CancelCheck(this);
     EndNetLogEvent(NetLog::TYPE_SAFE_BROWSING_CHECKING_URL, "result",
                    "request_canceled");
   }
 }

 // Note on net_log calls: TYPE_SAFE_BROWSING_DEFERRED events must be wholly
 // nested within TYPE_SAFE_BROWSING_CHECKING_URL events.  Synchronous checks
 // are not logged at all.
 void SafeBrowsingResourceThrottle::BeginNetLogEvent(NetLog::EventType type,
                                                     const GURL& url,
                                                     const char* name,
                                                     const char* value) {
   bound_net_log_.BeginEvent(
       type, base::Bind(&NetLogUrlCallback, request_, url, name, value));
   request_->net_log().AddEvent(
       type, bound_net_log_.source().ToEventParametersCallback());
 }

 void SafeBrowsingResourceThrottle::EndNetLogEvent(NetLog::EventType type,
                                                   const char* name,
                                                   const char* value) {
   bound_net_log_.EndEvent(
       type, base::Bind(&NetLogStringCallback, name, value));
   request_->net_log().AddEvent(
       type, bound_net_log_.source().ToEventParametersCallback());
 }

 void SafeBrowsingResourceThrottle::WillStartRequest(bool* defer) {
   // We need to check the new URL before starting the request.
   if (CheckUrl(request_->url()))
     return;

   // We let the check run in parallel with resource load only if this
   // db_manager only supports asynchronous checks, like on mobile.
   // Otherwise, we defer now.
   if (database_manager_->ChecksAreAlwaysAsync())
     return;

   // If the URL couldn't be verified synchronously, defer starting the
   // request until the check has completed.
   defer_state_ = DEFERRED_START;
   defer_start_time_ = base::TimeTicks::Now();
   *defer = true;
   BeginNetLogEvent(NetLog::TYPE_SAFE_BROWSING_DEFERRED, request_->url(),
                    "defer_reason", "at_start");
 }

 void SafeBrowsingResourceThrottle::WillProcessResponse(bool* defer) {
   CHECK_EQ(defer_state_, DEFERRED_NONE);
   // TODO(nparker): Maybe remove this check, since it should have no effect.
   if (!database_manager_->ChecksAreAlwaysAsync())
     return;

   if (state_ == STATE_CHECKING_URL ||
       state_ == STATE_DISPLAYING_BLOCKING_PAGE) {
     defer_state_ = DEFERRED_PROCESSING;
     defer_start_time_ = base::TimeTicks::Now();
     *defer = true;
     BeginNetLogEvent(NetLog::TYPE_SAFE_BROWSING_DEFERRED, request_->url(),
                      "defer_reason", "at_response");
   }
 }

 void SafeBrowsingResourceThrottle::WillRedirectRequest(
     const net::RedirectInfo& redirect_info,
     bool* defer) {
   CHECK_EQ(defer_state_, DEFERRED_NONE);

   // Prev check completed and was safe.
   if (state_ == STATE_NONE) {
     // Save the redirect urls for possible malware detail reporting later.
     redirect_urls_.push_back(redirect_info.new_url);

     // We need to check the new URL before following the redirect.
     if (CheckUrl(redirect_info.new_url))
       return;
     defer_state_ = DEFERRED_REDIRECT;
   } else {
     CHECK(state_ == STATE_CHECKING_URL ||
           state_ == STATE_DISPLAYING_BLOCKING_PAGE);
     // We can't check this new URL until we have finished checking
     // the prev one, or resumed from the blocking page.
     unchecked_redirect_url_ = redirect_info.new_url;
     defer_state_ = DEFERRED_UNCHECKED_REDIRECT;
   }

   defer_start_time_ = base::TimeTicks::Now();
   *defer = true;
   BeginNetLogEvent(
       NetLog::TYPE_SAFE_BROWSING_DEFERRED, redirect_info.new_url,
       "defer_reason",
       defer_state_ == DEFERRED_REDIRECT ? "redirect" : "unchecked_redirect");
 }

 const char* SafeBrowsingResourceThrottle::GetNameForLogging() const {
   return "SafeBrowsingResourceThrottle";
 }

 // SafeBrowsingService::Client implementation, called on the IO thread once
 // the URL has been classified.
 void SafeBrowsingResourceThrottle::OnCheckBrowseUrlResult(
     const GURL& url,
     safe_browsing::SBThreatType threat_type,
     const std::string& metadata) {
   CHECK_EQ(state_, STATE_CHECKING_URL);
   CHECK_EQ(url, url_being_checked_);

   timer_.Stop();  // Cancel the timeout timer.
   threat_type_ = threat_type;
   state_ = STATE_NONE;

   if (defer_state_ != DEFERRED_NONE) {
     EndNetLogEvent(NetLog::TYPE_SAFE_BROWSING_DEFERRED, nullptr, nullptr);
   }
   EndNetLogEvent(
       NetLog::TYPE_SAFE_BROWSING_CHECKING_URL, "result",
       threat_type_ == safe_browsing::SB_THREAT_TYPE_SAFE ? "safe" : "unsafe");

   if (threat_type == safe_browsing::SB_THREAT_TYPE_SAFE) {
     RecordHistogramResourceTypeSafe(resource_type_);
     if (defer_state_ != DEFERRED_NONE) {
       // Log how much time the safe browsing check cost us.
       ui_manager_->LogPauseDelay(base::TimeTicks::Now() - defer_start_time_);
       ResumeRequest();
     } else {
       ui_manager_->LogPauseDelay(base::TimeDelta());
     }
     return;
   }

   if (request_->load_flags() & net::LOAD_PREFETCH) {
     // Don't prefetch resources that fail safe browsing, disallow them.
     controller()->Cancel();
     UMA_HISTOGRAM_ENUMERATION("SB2.ResourceTypes2.UnsafePrefetchCanceled",
                               resource_type_, content::RESOURCE_TYPE_LAST_TYPE);
     return;
   }

   UMA_HISTOGRAM_ENUMERATION("SB2.ResourceTypes2.Unsafe", resource_type_,
                             content::RESOURCE_TYPE_LAST_TYPE);

   const content::ResourceRequestInfo* info =
       content::ResourceRequestInfo::ForRequest(request_);

   SafeBrowsingUIManager::UnsafeResource resource;
   resource.url = url;
   resource.original_url = request_->original_url();
   resource.redirect_urls = redirect_urls_;
   resource.is_subresource = resource_type_ != content::RESOURCE_TYPE_MAIN_FRAME;
   resource.is_subframe = resource_type_ == content::RESOURCE_TYPE_SUB_FRAME;
   resource.threat_type = threat_type;
   resource.threat_metadata = metadata;
   resource.callback = base::Bind(
       &SafeBrowsingResourceThrottle::OnBlockingPageComplete, AsWeakPtr());
   resource.callback_thread =
       content::BrowserThread::GetMessageLoopProxyForThread(
           content::BrowserThread::IO);
   resource.render_process_host_id = info->GetChildID();
   resource.render_view_id = info->GetRouteID();
   resource.threat_source = database_manager_->GetThreatSource();

   state_ = STATE_DISPLAYING_BLOCKING_PAGE;

   content::BrowserThread::PostTask(
       content::BrowserThread::UI,
       FROM_HERE,
       base::Bind(&SafeBrowsingResourceThrottle::StartDisplayingBlockingPage,
                  AsWeakPtr(), ui_manager_, resource));
 }

 void SafeBrowsingResourceThrottle::StartDisplayingBlockingPage(
     const base::WeakPtr<SafeBrowsingResourceThrottle>& throttle,
     scoped_refptr<SafeBrowsingUIManager> ui_manager,
     const SafeBrowsingUIManager::UnsafeResource& resource) {
   content::RenderViewHost* rvh = content::RenderViewHost::FromID(
       resource.render_process_host_id, resource.render_view_id);
   if (rvh) {
     content::WebContents* web_contents =
         content::WebContents::FromRenderViewHost(rvh);
     prerender::PrerenderContents* prerender_contents =
         prerender::PrerenderContents::FromWebContents(web_contents);

     if (prerender_contents) {
       prerender_contents->Destroy(prerender::FINAL_STATUS_SAFE_BROWSING);
     } else {
       ui_manager->DisplayBlockingPage(resource);
       return;
     }
   }

   // Tab is gone or it's being prerendered.
   content::BrowserThread::PostTask(
       content::BrowserThread::IO,
       FROM_HERE,
       base::Bind(&SafeBrowsingResourceThrottle::Cancel, throttle));
 }

 void SafeBrowsingResourceThrottle::Cancel() {
   controller()->Cancel();
 }

 // SafeBrowsingService::UrlCheckCallback implementation, called on the IO
 // thread when the user has decided to proceed with the current request, or
 // go back.
 void SafeBrowsingResourceThrottle::OnBlockingPageComplete(bool proceed) {
   CHECK_EQ(state_, STATE_DISPLAYING_BLOCKING_PAGE);
   state_ = STATE_NONE;

   if (proceed) {
     threat_type_ = safe_browsing::SB_THREAT_TYPE_SAFE;
     if (defer_state_ != DEFERRED_NONE) {
       ResumeRequest();
     }
   } else {
     controller()->Cancel();
   }
 }

 bool SafeBrowsingResourceThrottle::CheckUrl(const GURL& url) {
   CHECK_EQ(state_, STATE_NONE);
   // To reduce aggregate latency on mobile, check only the most dangerous
   // resource types.
   if (!database_manager_->CanCheckResourceType(resource_type_)) {
     UMA_HISTOGRAM_ENUMERATION("SB2.ResourceTypes2.Skipped", resource_type_,
                               content::RESOURCE_TYPE_LAST_TYPE);
     return true;
   }

   bool succeeded_synchronously = database_manager_->CheckBrowseUrl(url, this);
   UMA_HISTOGRAM_ENUMERATION("SB2.ResourceTypes2.Checked", resource_type_,
                             content::RESOURCE_TYPE_LAST_TYPE);

   if (succeeded_synchronously) {
     RecordHistogramResourceTypeSafe(resource_type_);
     threat_type_ = safe_browsing::SB_THREAT_TYPE_SAFE;
     ui_manager_->LogPauseDelay(base::TimeDelta());  // No delay.
     return true;
   }

   state_ = STATE_CHECKING_URL;
   url_being_checked_ = url;
   BeginNetLogEvent(NetLog::TYPE_SAFE_BROWSING_CHECKING_URL, url, nullptr,
                    nullptr);

   // Start a timer to abort the check if it takes too long.
   // TODO(nparker): Set this only when we defer, based on remaining time,
   // so we don't cancel earlier than necessary.
   timer_.Start(FROM_HERE,
                base::TimeDelta::FromMilliseconds(kCheckUrlTimeoutMs),
                this, &SafeBrowsingResourceThrottle::OnCheckUrlTimeout);

   return false;
 }

 void SafeBrowsingResourceThrottle::OnCheckUrlTimeout() {
   CHECK_EQ(state_, STATE_CHECKING_URL);

   database_manager_->CancelCheck(this);
   OnCheckBrowseUrlResult(
       url_being_checked_, safe_browsing::SB_THREAT_TYPE_SAFE, std::string());
 }

 void SafeBrowsingResourceThrottle::ResumeRequest() {
   CHECK_EQ(state_, STATE_NONE);
   CHECK_NE(defer_state_, DEFERRED_NONE);

   bool resume = true;
   if (defer_state_ == DEFERRED_UNCHECKED_REDIRECT) {
     // Save the redirect urls for possible malware detail reporting later.
     redirect_urls_.push_back(unchecked_redirect_url_);
     if (!CheckUrl(unchecked_redirect_url_)) {
       // We're now waiting for the unchecked_redirect_url_.
       defer_state_ = DEFERRED_REDIRECT;
       resume = false;
       BeginNetLogEvent(NetLog::TYPE_SAFE_BROWSING_DEFERRED,
                        unchecked_redirect_url_, "defer_reason",
                        "resumed_redirect");
     }
   }

   if (resume) {
     defer_state_ = DEFERRED_NONE;
     controller()->Resume();
   }
 }
	// 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.

	#include "chrome/browser/renderer_host/safe_browsing_resource_throttle.h"

	#include "base/logging.h"
	#include "base/metrics/histogram_macros.h"
	#include "base/values.h"
	#include "chrome/browser/browser_process.h"
	#include "chrome/browser/prerender/prerender_contents.h"
	#include "chrome/browser/safe_browsing/safe_browsing_service.h"
	#include "content/public/browser/browser_thread.h"
	#include "content/public/browser/render_view_host.h"
	#include "content/public/browser/resource_controller.h"
	#include "content/public/browser/resource_request_info.h"
	#include "content/public/browser/web_contents.h"
	#include "net/base/load_flags.h"
	#include "net/log/net_log.h"
	#include "net/url_request/redirect_info.h"
	#include "net/url_request/url_request.h"

	using net::NetLog;
	using safe_browsing::SafeBrowsingUIManager;

	namespace {

	// Maximum time in milliseconds to wait for the safe browsing service to
	// verify a URL. After this amount of time the outstanding check will be
	// aborted, and the URL will be treated as if it were safe.
	const int kCheckUrlTimeoutMs = 5000;

	void RecordHistogramResourceTypeSafe(content::ResourceType resource_type) {
	UMA_HISTOGRAM_ENUMERATION("SB2.ResourceTypes2.Safe", resource_type,
	content::RESOURCE_TYPE_LAST_TYPE);
	}

	// Return a dictionary with "url"=\|url-spec\| and optionally
	// \|name\|=\|value\| (if not null), for netlogging.
	// This will also add a reference to the original request's net_log ID.
	scoped_ptr<base::Value> NetLogUrlCallback(
	const net::URLRequest* request,
	const GURL& url,
	const char* name,
	const char* value,
	net::NetLogCaptureMode /* capture_mode */) {
	scoped_ptr<base::DictionaryValue> event_params(new base::DictionaryValue());
	event_params->SetString("url", url.spec());
	if (name && value)
	event_params->SetString(name, value);
	request->net_log().source().AddToEventParameters(event_params.get());
	return event_params.Pass();
	}

	// Return a dictionary with \|name\|=\|value\|, for netlogging.
	scoped_ptr<base::Value> NetLogStringCallback(
	const char* name,
	const char* value,
	net::NetLogCaptureMode) {
	scoped_ptr<base::DictionaryValue> event_params(new base::DictionaryValue());
	if (name && value)
	event_params->SetString(name, value);
	return event_params.Pass();
	}

	} // namespace

	// TODO(eroman): Downgrade these CHECK()s to DCHECKs once there is more
	// unit test coverage.

	// static
	SafeBrowsingResourceThrottle* SafeBrowsingResourceThrottle::MaybeCreate(
	net::URLRequest* request,
	content::ResourceType resource_type,
	safe_browsing::SafeBrowsingService* sb_service) {
	if (sb_service->database_manager()->IsSupported()) {
	return new SafeBrowsingResourceThrottle(request, resource_type, sb_service);
	}
	return nullptr;
	}

	SafeBrowsingResourceThrottle::SafeBrowsingResourceThrottle(
	const net::URLRequest* request,
	content::ResourceType resource_type,
	safe_browsing::SafeBrowsingService* sb_service)
	: state_(STATE_NONE),
	defer_state_(DEFERRED_NONE),
	threat_type_(safe_browsing::SB_THREAT_TYPE_SAFE),
	database_manager_(sb_service->database_manager()),
	ui_manager_(sb_service->ui_manager()),
	request_(request),
	resource_type_(resource_type),
	bound_net_log_(net::BoundNetLog::Make(request->net_log().net_log(),
	NetLog::SOURCE_SAFE_BROWSING)) {}

	SafeBrowsingResourceThrottle::~SafeBrowsingResourceThrottle() {
	if (defer_state_ != DEFERRED_NONE) {
	EndNetLogEvent(NetLog::TYPE_SAFE_BROWSING_DEFERRED, nullptr, nullptr);
	}

	if (state_ == STATE_CHECKING_URL) {
	database_manager_->CancelCheck(this);
	EndNetLogEvent(NetLog::TYPE_SAFE_BROWSING_CHECKING_URL, "result",
	"request_canceled");
	}
	}

	// Note on net_log calls: TYPE_SAFE_BROWSING_DEFERRED events must be wholly
	// nested within TYPE_SAFE_BROWSING_CHECKING_URL events. Synchronous checks
	// are not logged at all.
	void SafeBrowsingResourceThrottle::BeginNetLogEvent(NetLog::EventType type,
	const GURL& url,
	const char* name,
	const char* value) {
	bound_net_log_.BeginEvent(
	type, base::Bind(&NetLogUrlCallback, request_, url, name, value));
	request_->net_log().AddEvent(
	type, bound_net_log_.source().ToEventParametersCallback());
	}

	void SafeBrowsingResourceThrottle::EndNetLogEvent(NetLog::EventType type,
	const char* name,
	const char* value) {
	bound_net_log_.EndEvent(
	type, base::Bind(&NetLogStringCallback, name, value));
	request_->net_log().AddEvent(
	type, bound_net_log_.source().ToEventParametersCallback());
	}

	void SafeBrowsingResourceThrottle::WillStartRequest(bool* defer) {
	// We need to check the new URL before starting the request.
	if (CheckUrl(request_->url()))
	return;

	// We let the check run in parallel with resource load only if this
	// db_manager only supports asynchronous checks, like on mobile.
	// Otherwise, we defer now.
	if (database_manager_->ChecksAreAlwaysAsync())
	return;

	// If the URL couldn't be verified synchronously, defer starting the
	// request until the check has completed.
	defer_state_ = DEFERRED_START;
	defer_start_time_ = base::TimeTicks::Now();
	*defer = true;
	BeginNetLogEvent(NetLog::TYPE_SAFE_BROWSING_DEFERRED, request_->url(),
	"defer_reason", "at_start");
	}

	void SafeBrowsingResourceThrottle::WillProcessResponse(bool* defer) {
	CHECK_EQ(defer_state_, DEFERRED_NONE);
	// TODO(nparker): Maybe remove this check, since it should have no effect.
	if (!database_manager_->ChecksAreAlwaysAsync())
	return;

	if (state_ == STATE_CHECKING_URL \|\|
	state_ == STATE_DISPLAYING_BLOCKING_PAGE) {
	defer_state_ = DEFERRED_PROCESSING;
	defer_start_time_ = base::TimeTicks::Now();
	*defer = true;
	BeginNetLogEvent(NetLog::TYPE_SAFE_BROWSING_DEFERRED, request_->url(),
	"defer_reason", "at_response");
	}
	}

	void SafeBrowsingResourceThrottle::WillRedirectRequest(
	const net::RedirectInfo& redirect_info,
	bool* defer) {
	CHECK_EQ(defer_state_, DEFERRED_NONE);

	// Prev check completed and was safe.
	if (state_ == STATE_NONE) {
	// Save the redirect urls for possible malware detail reporting later.
	redirect_urls_.push_back(redirect_info.new_url);

	// We need to check the new URL before following the redirect.
	if (CheckUrl(redirect_info.new_url))
	return;
	defer_state_ = DEFERRED_REDIRECT;
	} else {
	CHECK(state_ == STATE_CHECKING_URL \|\|
	state_ == STATE_DISPLAYING_BLOCKING_PAGE);
	// We can't check this new URL until we have finished checking
	// the prev one, or resumed from the blocking page.
	unchecked_redirect_url_ = redirect_info.new_url;
	defer_state_ = DEFERRED_UNCHECKED_REDIRECT;
	}

	defer_start_time_ = base::TimeTicks::Now();
	*defer = true;
	BeginNetLogEvent(
	NetLog::TYPE_SAFE_BROWSING_DEFERRED, redirect_info.new_url,
	"defer_reason",
	defer_state_ == DEFERRED_REDIRECT ? "redirect" : "unchecked_redirect");
	}

	const char* SafeBrowsingResourceThrottle::GetNameForLogging() const {
	return "SafeBrowsingResourceThrottle";
	}

	// SafeBrowsingService::Client implementation, called on the IO thread once
	// the URL has been classified.
	void SafeBrowsingResourceThrottle::OnCheckBrowseUrlResult(
	const GURL& url,
	safe_browsing::SBThreatType threat_type,
	const std::string& metadata) {
	CHECK_EQ(state_, STATE_CHECKING_URL);
	CHECK_EQ(url, url_being_checked_);

	timer_.Stop(); // Cancel the timeout timer.
	threat_type_ = threat_type;
	state_ = STATE_NONE;

	if (defer_state_ != DEFERRED_NONE) {
	EndNetLogEvent(NetLog::TYPE_SAFE_BROWSING_DEFERRED, nullptr, nullptr);
	}
	EndNetLogEvent(
	NetLog::TYPE_SAFE_BROWSING_CHECKING_URL, "result",
	threat_type_ == safe_browsing::SB_THREAT_TYPE_SAFE ? "safe" : "unsafe");

	if (threat_type == safe_browsing::SB_THREAT_TYPE_SAFE) {
	RecordHistogramResourceTypeSafe(resource_type_);
	if (defer_state_ != DEFERRED_NONE) {
	// Log how much time the safe browsing check cost us.
	ui_manager_->LogPauseDelay(base::TimeTicks::Now() - defer_start_time_);
	ResumeRequest();
	} else {
	ui_manager_->LogPauseDelay(base::TimeDelta());
	}
	return;
	}

	if (request_->load_flags() & net::LOAD_PREFETCH) {
	// Don't prefetch resources that fail safe browsing, disallow them.
	controller()->Cancel();
	UMA_HISTOGRAM_ENUMERATION("SB2.ResourceTypes2.UnsafePrefetchCanceled",
	resource_type_, content::RESOURCE_TYPE_LAST_TYPE);
	return;
	}

	UMA_HISTOGRAM_ENUMERATION("SB2.ResourceTypes2.Unsafe", resource_type_,
	content::RESOURCE_TYPE_LAST_TYPE);

	const content::ResourceRequestInfo* info =
	content::ResourceRequestInfo::ForRequest(request_);

	SafeBrowsingUIManager::UnsafeResource resource;
	resource.url = url;
	resource.original_url = request_->original_url();
	resource.redirect_urls = redirect_urls_;
	resource.is_subresource = resource_type_ != content::RESOURCE_TYPE_MAIN_FRAME;
	resource.is_subframe = resource_type_ == content::RESOURCE_TYPE_SUB_FRAME;
	resource.threat_type = threat_type;
	resource.threat_metadata = metadata;
	resource.callback = base::Bind(
	&SafeBrowsingResourceThrottle::OnBlockingPageComplete, AsWeakPtr());
	resource.callback_thread =
	content::BrowserThread::GetMessageLoopProxyForThread(
	content::BrowserThread::IO);
	resource.render_process_host_id = info->GetChildID();
	resource.render_view_id = info->GetRouteID();
	resource.threat_source = database_manager_->GetThreatSource();

	state_ = STATE_DISPLAYING_BLOCKING_PAGE;

	content::BrowserThread::PostTask(
	content::BrowserThread::UI,
	FROM_HERE,
	base::Bind(&SafeBrowsingResourceThrottle::StartDisplayingBlockingPage,
	AsWeakPtr(), ui_manager_, resource));
	}

	void SafeBrowsingResourceThrottle::StartDisplayingBlockingPage(
	const base::WeakPtr<SafeBrowsingResourceThrottle>& throttle,
	scoped_refptr<SafeBrowsingUIManager> ui_manager,
	const SafeBrowsingUIManager::UnsafeResource& resource) {
	content::RenderViewHost* rvh = content::RenderViewHost::FromID(
	resource.render_process_host_id, resource.render_view_id);
	if (rvh) {
	content::WebContents* web_contents =
	content::WebContents::FromRenderViewHost(rvh);
	prerender::PrerenderContents* prerender_contents =
	prerender::PrerenderContents::FromWebContents(web_contents);

	if (prerender_contents) {
	prerender_contents->Destroy(prerender::FINAL_STATUS_SAFE_BROWSING);
	} else {
	ui_manager->DisplayBlockingPage(resource);
	return;
	}
	}

	// Tab is gone or it's being prerendered.
	content::BrowserThread::PostTask(
	content::BrowserThread::IO,
	FROM_HERE,
	base::Bind(&SafeBrowsingResourceThrottle::Cancel, throttle));
	}

	void SafeBrowsingResourceThrottle::Cancel() {
	controller()->Cancel();
	}

	// SafeBrowsingService::UrlCheckCallback implementation, called on the IO
	// thread when the user has decided to proceed with the current request, or
	// go back.
	void SafeBrowsingResourceThrottle::OnBlockingPageComplete(bool proceed) {
	CHECK_EQ(state_, STATE_DISPLAYING_BLOCKING_PAGE);
	state_ = STATE_NONE;

	if (proceed) {
	threat_type_ = safe_browsing::SB_THREAT_TYPE_SAFE;
	if (defer_state_ != DEFERRED_NONE) {
	ResumeRequest();
	}
	} else {
	controller()->Cancel();
	}
	}

	bool SafeBrowsingResourceThrottle::CheckUrl(const GURL& url) {
	CHECK_EQ(state_, STATE_NONE);
	// To reduce aggregate latency on mobile, check only the most dangerous
	// resource types.
	if (!database_manager_->CanCheckResourceType(resource_type_)) {
	UMA_HISTOGRAM_ENUMERATION("SB2.ResourceTypes2.Skipped", resource_type_,
	content::RESOURCE_TYPE_LAST_TYPE);
	return true;
	}

	bool succeeded_synchronously = database_manager_->CheckBrowseUrl(url, this);
	UMA_HISTOGRAM_ENUMERATION("SB2.ResourceTypes2.Checked", resource_type_,
	content::RESOURCE_TYPE_LAST_TYPE);

	if (succeeded_synchronously) {
	RecordHistogramResourceTypeSafe(resource_type_);
	threat_type_ = safe_browsing::SB_THREAT_TYPE_SAFE;
	ui_manager_->LogPauseDelay(base::TimeDelta()); // No delay.
	return true;
	}

	state_ = STATE_CHECKING_URL;
	url_being_checked_ = url;
	BeginNetLogEvent(NetLog::TYPE_SAFE_BROWSING_CHECKING_URL, url, nullptr,
	nullptr);

	// Start a timer to abort the check if it takes too long.
	// TODO(nparker): Set this only when we defer, based on remaining time,
	// so we don't cancel earlier than necessary.
	timer_.Start(FROM_HERE,
	base::TimeDelta::FromMilliseconds(kCheckUrlTimeoutMs),
	this, &SafeBrowsingResourceThrottle::OnCheckUrlTimeout);

	return false;
	}

	void SafeBrowsingResourceThrottle::OnCheckUrlTimeout() {
	CHECK_EQ(state_, STATE_CHECKING_URL);

	database_manager_->CancelCheck(this);
	OnCheckBrowseUrlResult(
	url_being_checked_, safe_browsing::SB_THREAT_TYPE_SAFE, std::string());
	}

	void SafeBrowsingResourceThrottle::ResumeRequest() {
	CHECK_EQ(state_, STATE_NONE);
	CHECK_NE(defer_state_, DEFERRED_NONE);

	bool resume = true;
	if (defer_state_ == DEFERRED_UNCHECKED_REDIRECT) {
	// Save the redirect urls for possible malware detail reporting later.
	redirect_urls_.push_back(unchecked_redirect_url_);
	if (!CheckUrl(unchecked_redirect_url_)) {
	// We're now waiting for the unchecked_redirect_url_.
	defer_state_ = DEFERRED_REDIRECT;
	resume = false;
	BeginNetLogEvent(NetLog::TYPE_SAFE_BROWSING_DEFERRED,
	unchecked_redirect_url_, "defer_reason",
	"resumed_redirect");
	}
	}

	if (resume) {
	defer_state_ = DEFERRED_NONE;
	controller()->Resume();
	}
	}