// Copyright 2018 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 "gpu/command_buffer/service/shared_image_backing_factory_ahardwarebuffer.h"

#include <sync/sync.h>

#include "base/android/android_hardware_buffer_compat.h"
#include "base/android/scoped_hardware_buffer_handle.h"
#include "base/logging.h"
#include "components/viz/common/gpu/vulkan_context_provider.h"
#include "components/viz/common/resources/resource_format_utils.h"
#include "components/viz/common/resources/resource_sizes.h"
#include "gpu/command_buffer/common/gles2_cmd_utils.h"
#include "gpu/command_buffer/common/shared_image_usage.h"
#include "gpu/command_buffer/service/ahardwarebuffer_utils.h"
#include "gpu/command_buffer/service/gles2_cmd_decoder.h"
#include "gpu/command_buffer/service/mailbox_manager.h"
#include "gpu/command_buffer/service/memory_tracking.h"
#include "gpu/command_buffer/service/raster_decoder_context_state.h"
#include "gpu/command_buffer/service/shared_image_backing.h"
#include "gpu/command_buffer/service/shared_image_representation.h"
#include "gpu/command_buffer/service/skia_utils.h"
#include "gpu/command_buffer/service/texture_manager.h"
#include "gpu/ipc/common/android/android_image_reader_utils.h"
#include "gpu/vulkan/vulkan_device_queue.h"
#include "gpu/vulkan/vulkan_function_pointers.h"
#include "gpu/vulkan/vulkan_implementation.h"
#include "third_party/skia/include/gpu/GrBackendSemaphore.h"
#include "third_party/skia/include/gpu/GrBackendSurface.h"
#include "ui/gfx/color_space.h"
#include "ui/gfx/geometry/size.h"
#include "ui/gl/gl_context.h"
#include "ui/gl/gl_fence_android_native_fence_sync.h"
#include "ui/gl/gl_gl_api_implementation.h"
#include "ui/gl/gl_image_ahardwarebuffer.h"
#include "ui/gl/gl_version_info.h"

namespace gpu {

// Implementation of SharedImageBacking that holds an AHardwareBuffer. This
// can be used to create a GL texture or a VK Image from the AHardwareBuffer
// backing.
class SharedImageBackingAHB : public SharedImageBacking {
 public:
  SharedImageBackingAHB(const Mailbox& mailbox,
                        viz::ResourceFormat format,
                        const gfx::Size& size,
                        const gfx::ColorSpace& color_space,
                        uint32_t usage,
                        base::android::ScopedHardwareBufferHandle handle,
                        size_t estimated_size,
                        raster::RasterDecoderContextState* context_state);

  ~SharedImageBackingAHB() override;

  bool IsCleared() const override;
  void SetCleared() override;
  void Update() override;
  bool ProduceLegacyMailbox(MailboxManager* mailbox_manager) override;
  void Destroy() override;
  raster::RasterDecoderContextState* GetContextState() const;
  base::ScopedFD TakeGLWriteSyncFd();
  base::ScopedFD TakeVkReadSyncFd();
  base::android::ScopedHardwareBufferHandle GetAhbHandle();
  void SetGLWriteSyncFd(base::ScopedFD fd);
  void SetVkReadSyncFd(base::ScopedFD fd);

 protected:
  std::unique_ptr<SharedImageRepresentationGLTexture> ProduceGLTexture(
      SharedImageManager* manager,
      MemoryTypeTracker* tracker) override;

  std::unique_ptr<SharedImageRepresentationSkia> ProduceSkia(
      SharedImageManager* manager,
      MemoryTypeTracker* tracker) override;

 private:
  bool GenGLTexture();
  base::android::ScopedHardwareBufferHandle hardware_buffer_handle_;

  // This texture will be lazily initialised/created when ProduceGLTexture is
  // called.
  gles2::Texture* texture_ = nullptr;

  // TODO(vikassoni): In future when we add begin/end write support, we will
  // need to properly use this flag to pass the is_cleared_ information to
  // the GL texture representation while begin write and back to this class from
  // the GL texture represntation after end write. This is because this class
  // will not know if SetCleared() arrives during begin write happening on GL
  // texture representation.
  bool is_cleared_ = false;
  raster::RasterDecoderContextState* context_state_ = nullptr;
  base::ScopedFD gl_write_sync_fd_;
  base::ScopedFD vk_read_sync_fd_;

  DISALLOW_COPY_AND_ASSIGN(SharedImageBackingAHB);
};

// Representation of a SharedImageBackingAHB as a GL Texture.
class SharedImageRepresentationGLTextureAHB
    : public SharedImageRepresentationGLTexture {
 public:
  SharedImageRepresentationGLTextureAHB(SharedImageManager* manager,
                                        SharedImageBacking* backing,
                                        MemoryTypeTracker* tracker,
                                        gles2::Texture* texture)
      : SharedImageRepresentationGLTexture(manager, backing, tracker),
        texture_(texture) {}

  gles2::Texture* GetTexture() override { return texture_; }

  bool BeginAccess(GLenum mode) override {
    // TODO(vikassoni): Currently Skia Vk backing never does a write. So GL read
    // do not need to wait for the Vk write to finish. Eventually when Vk starts
    // writing, we will need to TakeVkWriteSyncFd() and wait on it for mode =
    // GL_SHARED_IMAGE_ACCESS_MODE_READ_CHROMIUM.

    // Wait on Vk read if GL is going to write.
    // TODO(vikassoni): GL writes should wait on both Vk read and Vk writes.
    if (mode == GL_SHARED_IMAGE_ACCESS_MODE_READWRITE_CHROMIUM) {
      base::ScopedFD sync_fd = ahb_backing()->TakeVkReadSyncFd();

      // Create an egl fence sync and do a server side wait.
      if (!InsertEglFenceAndWait(std::move(sync_fd)))
        return false;
    }
    mode_ = mode;
    return true;
  }

  void EndAccess() override {
    // TODO(vikassoni): Currently Skia Vk backing never does a write. So Vk
    // writes do not need to wait on GL to finish the read. Eventually when Vk
    // starts writing, we will need to create and set a GLReadSyncFd for mode =
    // GL_SHARED_IMAGE_ACCESS_MODE_READ_CHROMIUM for Vk to wait on it.
    if (mode_ == GL_SHARED_IMAGE_ACCESS_MODE_READWRITE_CHROMIUM) {
      base::ScopedFD sync_fd = CreateEglFenceAndExportFd();
      if (!sync_fd.is_valid())
        return;

      // Pass this fd to its backing.
      ahb_backing()->SetGLWriteSyncFd(std::move(sync_fd));
    }
  }

 private:
  SharedImageBackingAHB* ahb_backing() {
    return static_cast<SharedImageBackingAHB*>(backing());
  }

  gles2::Texture* texture_;
  GLenum mode_ = GL_SHARED_IMAGE_ACCESS_MODE_READ_CHROMIUM;

  DISALLOW_COPY_AND_ASSIGN(SharedImageRepresentationGLTextureAHB);
};

// GL backed Skia representation of SharedImageBackingAHB.
class SharedImageRepresentationSkiaGLAHB
    : public SharedImageRepresentationSkia {
 public:
  SharedImageRepresentationSkiaGLAHB(SharedImageManager* manager,
                                     SharedImageBacking* backing,
                                     MemoryTypeTracker* tracker,
                                     GLenum target,
                                     GLuint service_id)
      : SharedImageRepresentationSkia(manager, backing, tracker),
        target_(target),
        service_id_(service_id) {}

  ~SharedImageRepresentationSkiaGLAHB() override { DCHECK(!write_surface_); }

  sk_sp<SkSurface> BeginWriteAccess(
      GrContext* gr_context,
      int final_msaa_count,
      const SkSurfaceProps& surface_props) override {
    // if there is already a write_surface_, it means previous BeginWriteAccess
    // doesn't have a corresponding EndWriteAccess.
    if (write_surface_)
      return nullptr;

    // Synchronise this access with the Vk reads.
    // TODO(vikassoni): SkiaGL writes should wait on both Vk read and Vk writes.
    base::ScopedFD sync_fd = ahb_backing()->TakeVkReadSyncFd();

    // Create an egl fence sync and do a server side wait.
    if (!InsertEglFenceAndWait(std::move(sync_fd)))
      return nullptr;

    GrBackendTexture backend_texture;
    if (!GetGrBackendTexture(gl::GLContext::GetCurrent()->GetVersionInfo(),
                             target_, size(), service_id_, format(),
                             &backend_texture)) {
      return nullptr;
    }

    SkColorType sk_color_type = viz::ResourceFormatToClosestSkColorType(
        /*gpu_compositing=*/true, format());
    auto surface = SkSurface::MakeFromBackendTextureAsRenderTarget(
        gr_context, backend_texture, kTopLeft_GrSurfaceOrigin, final_msaa_count,
        sk_color_type, nullptr, &surface_props);
    write_surface_ = surface.get();
    return surface;
  }

  void EndWriteAccess(sk_sp<SkSurface> surface) override {
    DCHECK_EQ(surface.get(), write_surface_);
    DCHECK(surface->unique());
    // TODO(ericrk): Keep the surface around for re-use.
    write_surface_ = nullptr;

    // Insert a gl fence to signal the write completion. Vulkan representation
    // needs to wait on this signal before it can read from this.
    base::ScopedFD sync_fd = CreateEglFenceAndExportFd();
    if (!sync_fd.is_valid())
      return;

    // Pass this fd to its backing.
    ahb_backing()->SetGLWriteSyncFd(std::move(sync_fd));
  }

  bool BeginReadAccess(SkSurface* sk_surface,
                       GrBackendTexture* backend_texture) override {
    // TODO(vikassoni): Currently Skia Vk backing never does a write. So this
    // read do not need to wait for the Vk write to finish. Eventually when Vk
    // starts writing, we might need to TakeVkWriteSyncFd() and wait on it.
    if (!GetGrBackendTexture(gl::GLContext::GetCurrent()->GetVersionInfo(),
                             target_, size(), service_id_, format(),
                             backend_texture)) {
      return false;
    }
    return true;
  }

  void EndReadAccess() override {
    // TODO(vikassoni): Currently Skia Vk backing never does a write. So Vk
    // writes do not need to wait on this read to finish. Eventually when Vk
    // starts writing, we will need to create and set a SkiaGLReadSyncFd.
    // TODO(ericrk): Handle begin/end correctness checks.
  }

 private:
  SharedImageBackingAHB* ahb_backing() {
    return static_cast<SharedImageBackingAHB*>(backing());
  }

  GLenum target_;
  GLuint service_id_;
  SkSurface* write_surface_ = nullptr;
};

// Vk backed Skia representation of SharedImageBackingAHB.
class SharedImageRepresentationSkiaVkAHB
    : public SharedImageRepresentationSkia {
 public:
  SharedImageRepresentationSkiaVkAHB(SharedImageManager* manager,
                                     SharedImageBacking* backing)
      : SharedImageRepresentationSkia(manager, backing, nullptr) {
    SharedImageBackingAHB* ahb_backing =
        static_cast<SharedImageBackingAHB*>(backing);
    DCHECK(ahb_backing);
    raster::RasterDecoderContextState* context_state =
        ahb_backing->GetContextState();
    DCHECK(context_state);
    DCHECK(context_state->vk_context_provider);

    vk_device_ =
        context_state->vk_context_provider->GetDeviceQueue()->GetVulkanDevice();
    vk_phy_device_ = context_state->vk_context_provider->GetDeviceQueue()
                         ->GetVulkanPhysicalDevice();
    vk_implementation_ =
        context_state->vk_context_provider->GetVulkanImplementation();
  }

  ~SharedImageRepresentationSkiaVkAHB() override { DCHECK(!read_surface_); }

  sk_sp<SkSurface> BeginWriteAccess(
      GrContext* gr_context,
      int final_msaa_count,
      const SkSurfaceProps& surface_props) override {
    NOTIMPLEMENTED();
    return nullptr;
  }

  void EndWriteAccess(sk_sp<SkSurface> surface) override { NOTIMPLEMENTED(); }

  bool BeginReadAccess(SkSurface* sk_surface,
                       GrBackendTexture* backend_texture) override {
    // If previous read access has not ended.
    if (read_surface_)
      return false;
    DCHECK(sk_surface);
    DCHECK(backend_texture);

    // Synchronise the read access with the GL writes.
    base::ScopedFD sync_fd = ahb_backing()->TakeGLWriteSyncFd();

    // We need to wait only if there is a valid fd.
    if (sync_fd.is_valid()) {
      // Do a client side wait for now.
      // TODO(vikassoni): There seems to be a skia bug -
      // https://bugs.chromium.org/p/chromium/issues/detail?id=916812 currently
      // where wait() on the sk surface crashes. Remove the sync_wait() and
      // apply CL mentioned in the bug when the issue is fixed.
      static const int InfiniteSyncWaitTimeout = -1;
      if (sync_wait(sync_fd.get(), InfiniteSyncWaitTimeout) < 0) {
        LOG(ERROR) << "Failed while waiting on GL Write sync fd";
        return false;
      }
    }

    // Create a VkImage and import AHB.
    VkImage vk_image;
    VkImageCreateInfo vk_image_info;
    VkDeviceMemory vk_device_memory;
    VkDeviceSize mem_allocation_size;
    if (!vk_implementation_->CreateVkImageAndImportAHB(
            vk_device_, vk_phy_device_, size(), ahb_backing()->GetAhbHandle(),
            &vk_image, &vk_image_info, &vk_device_memory,
            &mem_allocation_size)) {
      return false;
    }

    // Create backend texture from the VkImage.
    GrVkAlloc alloc = {vk_device_memory, 0, mem_allocation_size, 0};
    GrVkImageInfo vk_info = {vk_image,
                             alloc,
                             vk_image_info.tiling,
                             vk_image_info.initialLayout,
                             vk_image_info.format,
                             vk_image_info.mipLevels};
    *backend_texture =
        GrBackendTexture(size().width(), size().height(), vk_info);
    if (!backend_texture->isValid()) {
      vkDestroyImage(vk_device_, vk_image, nullptr);
      vkFreeMemory(vk_device_, vk_device_memory, nullptr);
      return false;
    }

    // Cache the sk surface in the representation so that it can be used in the
    // EndReadAccess. Also make sure previous read_surface_ have been consumed
    // by EndReadAccess() call.
    read_surface_ = sk_surface;
    return true;
  }

  void EndReadAccess() override {
    // There should be a read_surface_ from the BeginReadAccess().
    DCHECK(read_surface_);

    // Create a vk semaphore which can be exported.
    VkExportSemaphoreCreateInfo export_info;
    export_info.sType = VK_STRUCTURE_TYPE_EXPORT_SEMAPHORE_CREATE_INFO;
    export_info.pNext = nullptr;
    export_info.handleTypes = VK_EXTERNAL_SEMAPHORE_HANDLE_TYPE_SYNC_FD_BIT;

    VkSemaphore vk_semaphore;
    VkSemaphoreCreateInfo sem_info;
    sem_info.sType = VK_STRUCTURE_TYPE_SEMAPHORE_CREATE_INFO;
    sem_info.pNext = &export_info;
    sem_info.flags = 0;
    bool result =
        vkCreateSemaphore(vk_device_, &sem_info, nullptr, &vk_semaphore);
    if (result != VK_SUCCESS) {
      // TODO(vikassoni): add more error handling rather than just return ?
      LOG(ERROR) << "vkCreateSemaphore failed";
      read_surface_ = nullptr;
      return;
    }
    GrBackendSemaphore gr_semaphore;
    gr_semaphore.initVulkan(vk_semaphore);

    // If GrSemaphoresSubmitted::kNo is returned, the GPU back-end did not
    // create or add any semaphores to signal on the GPU; the caller should not
    // instruct the GPU to wait on any of the semaphores.
    if (read_surface_->flushAndSignalSemaphores(1, &gr_semaphore) ==
        GrSemaphoresSubmitted::kNo) {
      vkDestroySemaphore(vk_device_, vk_semaphore, nullptr);
      read_surface_ = nullptr;
      return;
    }
    read_surface_ = nullptr;

    // All the pending SkSurface commands to the GPU-backed API are issued and
    // any SkSurface MSAA are resolved. After issuing all commands,
    // signalSemaphores of count numSemaphores semaphores are signaled by the
    // GPU. The caller must delete the semaphores created.
    // Export a sync fd from the semaphore.
    base::ScopedFD sync_fd;
    vk_implementation_->GetSemaphoreFdKHR(vk_device_, vk_semaphore, &sync_fd);

    // pass this sync fd to the backing.
    ahb_backing()->SetVkReadSyncFd(std::move(sync_fd));

    // TODO(vikassoni): We need to wait for the queue submission to complete
    // before we can destroy the semaphore. This will decrease the performance.
    // Add a future patch to handle this in more efficient way. Keep semaphores
    // in a STL queue instead of destroying it. Later use a fence to check if
    // the batch that refers the semaphore has completed execution. Delete the
    // semaphore once the fence is signalled.
    vkDeviceWaitIdle(vk_device_);
    vkDestroySemaphore(vk_device_, vk_semaphore, nullptr);
  }

 private:
  SharedImageBackingAHB* ahb_backing() {
    return static_cast<SharedImageBackingAHB*>(backing());
  }

  SkSurface* read_surface_ = nullptr;
  gpu::VulkanImplementation* vk_implementation_ = nullptr;
  VkDevice vk_device_ = VK_NULL_HANDLE;
  VkPhysicalDevice vk_phy_device_ = VK_NULL_HANDLE;
};

SharedImageBackingAHB::SharedImageBackingAHB(
    const Mailbox& mailbox,
    viz::ResourceFormat format,
    const gfx::Size& size,
    const gfx::ColorSpace& color_space,
    uint32_t usage,
    base::android::ScopedHardwareBufferHandle handle,
    size_t estimated_size,
    raster::RasterDecoderContextState* context_state)
    : SharedImageBacking(mailbox,
                         format,
                         size,
                         color_space,
                         usage,
                         estimated_size),
      hardware_buffer_handle_(std::move(handle)),
      context_state_(context_state) {
  DCHECK(hardware_buffer_handle_.is_valid());
}

SharedImageBackingAHB::~SharedImageBackingAHB() {
  // Check to make sure buffer is explicitly destroyed using Destroy() api
  // before this destructor is called.
  DCHECK(!hardware_buffer_handle_.is_valid());
  DCHECK(!texture_);
}

bool SharedImageBackingAHB::IsCleared() const {
  if (texture_)
    return texture_->IsLevelCleared(texture_->target(), 0);
  return is_cleared_;
}

void SharedImageBackingAHB::SetCleared() {
  if (texture_)
    texture_->SetLevelCleared(texture_->target(), 0, true);
  is_cleared_ = true;
}

void SharedImageBackingAHB::Update() {}

bool SharedImageBackingAHB::ProduceLegacyMailbox(
    MailboxManager* mailbox_manager) {
  DCHECK(hardware_buffer_handle_.is_valid());
  if (!GenGLTexture())
    return false;
  DCHECK(texture_);
  mailbox_manager->ProduceTexture(mailbox(), texture_);
  return true;
}

void SharedImageBackingAHB::Destroy() {
  DCHECK(hardware_buffer_handle_.is_valid());
  if (texture_) {
    texture_->RemoveLightweightRef(have_context());
    texture_ = nullptr;
  }
  hardware_buffer_handle_.reset();
}

raster::RasterDecoderContextState* SharedImageBackingAHB::GetContextState()
    const {
  return context_state_;
}

base::ScopedFD SharedImageBackingAHB::TakeGLWriteSyncFd() {
  return std::move(gl_write_sync_fd_);
}

void SharedImageBackingAHB::SetGLWriteSyncFd(base::ScopedFD fd) {
  gl_write_sync_fd_ = std::move(fd);
}

base::ScopedFD SharedImageBackingAHB::TakeVkReadSyncFd() {
  return std::move(vk_read_sync_fd_);
}

void SharedImageBackingAHB::SetVkReadSyncFd(base::ScopedFD fd) {
  vk_read_sync_fd_ = std::move(fd);
}

base::android::ScopedHardwareBufferHandle
SharedImageBackingAHB::GetAhbHandle() {
  return hardware_buffer_handle_.Clone();
}

std::unique_ptr<SharedImageRepresentationGLTexture>
SharedImageBackingAHB::ProduceGLTexture(SharedImageManager* manager,
                                        MemoryTypeTracker* tracker) {
  // Use same texture for all the texture representations generated from same
  // backing.
  if (!GenGLTexture())
    return nullptr;

  DCHECK(texture_);
  return std::make_unique<SharedImageRepresentationGLTextureAHB>(
      manager, this, tracker, texture_);
}

std::unique_ptr<SharedImageRepresentationSkia>
SharedImageBackingAHB::ProduceSkia(SharedImageManager* manager,
                                   MemoryTypeTracker* tracker) {
  DCHECK(context_state_);

  // Check whether we are in Vulkan mode OR GL mode and accordingly create
  // Skia representation.
  if (context_state_->use_vulkan_gr_context) {
    return std::make_unique<SharedImageRepresentationSkiaVkAHB>(manager, this);
  }

  if (!GenGLTexture())
    return nullptr;

  DCHECK(texture_);
  return std::make_unique<SharedImageRepresentationSkiaGLAHB>(
      manager, this, tracker, texture_->target(), texture_->service_id());
}

bool SharedImageBackingAHB::GenGLTexture() {
  if (texture_)
    return true;

  DCHECK(hardware_buffer_handle_.is_valid());

  // Target for AHB backed egl images.
  // Note that we are not using GL_TEXTURE_EXTERNAL_OES target since sksurface
  // doesn't supports it. As per the egl documentation -
  // https://www.khronos.org/registry/OpenGL/extensions/OES/OES_EGL_image_external.txt
  // if GL_OES_EGL_image is supported then <target> may also be TEXTURE_2D.
  GLenum target = GL_TEXTURE_2D;
  GLenum get_target = GL_TEXTURE_BINDING_2D;

  // Create a gles2 texture using the AhardwareBuffer.
  gl::GLApi* api = gl::g_current_gl_context;
  GLuint service_id = 0;
  api->glGenTexturesFn(1, &service_id);
  GLint old_texture_binding = 0;
  api->glGetIntegervFn(get_target, &old_texture_binding);
  api->glBindTextureFn(target, service_id);
  api->glTexParameteriFn(target, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  api->glTexParameteriFn(target, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  api->glTexParameteriFn(target, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
  api->glTexParameteriFn(target, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

  // Create an egl image using AHardwareBuffer.
  auto egl_image = base::MakeRefCounted<gl::GLImageAHardwareBuffer>(size());
  if (!egl_image->Initialize(hardware_buffer_handle_.get(), false)) {
    LOG(ERROR) << "Failed to create EGL image ";
    api->glBindTextureFn(target, old_texture_binding);
    api->glDeleteTexturesFn(1, &service_id);
    return false;
  }
  if (!egl_image->BindTexImage(target)) {
    LOG(ERROR) << "Failed to bind egl image";
    api->glBindTextureFn(target, old_texture_binding);
    api->glDeleteTexturesFn(1, &service_id);
    return false;
  }

  // Create a gles2 Texture.
  texture_ = new gles2::Texture(service_id);
  texture_->SetLightweightRef();
  texture_->SetTarget(target, 1);
  texture_->sampler_state_.min_filter = GL_LINEAR;
  texture_->sampler_state_.mag_filter = GL_LINEAR;
  texture_->sampler_state_.wrap_t = GL_CLAMP_TO_EDGE;
  texture_->sampler_state_.wrap_s = GL_CLAMP_TO_EDGE;

  // If the backing is already cleared, no need to clear it again.
  gfx::Rect cleared_rect;
  if (is_cleared_)
    cleared_rect = gfx::Rect(size());

  GLenum gl_format = viz::GLDataFormat(format());
  GLenum gl_type = viz::GLDataType(format());
  texture_->SetLevelInfo(target, 0, egl_image->GetInternalFormat(),
                         size().width(), size().height(), 1, 0, gl_format,
                         gl_type, cleared_rect);
  texture_->SetLevelImage(target, 0, egl_image.get(), gles2::Texture::BOUND);
  texture_->SetImmutable(true);
  api->glBindTextureFn(target, old_texture_binding);
  DCHECK_EQ(egl_image->GetInternalFormat(), gl_format);
  return true;
}

SharedImageBackingFactoryAHB::SharedImageBackingFactoryAHB(
    const GpuDriverBugWorkarounds& workarounds,
    const GpuFeatureInfo& gpu_feature_info,
    raster::RasterDecoderContextState* context_state)
    : context_state_(context_state) {
  scoped_refptr<gles2::FeatureInfo> feature_info =
      new gles2::FeatureInfo(workarounds, gpu_feature_info);
  feature_info->Initialize(ContextType::CONTEXT_TYPE_OPENGLES2, false,
                           gles2::DisallowedFeatures());
  const gles2::Validators* validators = feature_info->validators();
  const bool is_egl_image_supported =
      gl::g_current_gl_driver->ext.b_GL_OES_EGL_image;

  // Build the feature info for all the resource formats.
  for (int i = 0; i <= viz::RESOURCE_FORMAT_MAX; ++i) {
    auto format = static_cast<viz::ResourceFormat>(i);
    FormatInfo& info = format_info_[i];

    // If AHB does not support this format, we will not be able to create this
    // backing.
    if (!AHardwareBufferSupportedFormat(format))
      continue;

    info.ahb_supported = true;
    info.ahb_format = AHardwareBufferFormat(format);

    // TODO(vikassoni): In future when we use GL_TEXTURE_EXTERNAL_OES target
    // with AHB, we need to check if oes_egl_image_external is supported or
    // not.
    if (!is_egl_image_supported)
      continue;

    // Check if AHB backed GL texture can be created using this format and
    // gather GL related format info.
    // TODO(vikassoni): Add vulkan related information in future.
    GLuint internal_format = viz::GLInternalFormat(format);
    GLenum gl_format = viz::GLDataFormat(format);
    GLenum gl_type = viz::GLDataType(format);

    //  GLImageAHardwareBuffer supports internal format GL_RGBA and GL_RGB.
    if (internal_format != GL_RGBA && internal_format != GL_RGB)
      continue;

    // Validate if GL format, type and internal format is supported.
    if (validators->texture_internal_format.IsValid(internal_format) &&
        validators->texture_format.IsValid(gl_format) &&
        validators->pixel_type.IsValid(gl_type)) {
      info.gl_supported = true;
      info.gl_format = gl_format;
      info.gl_type = gl_type;
      info.internal_format = internal_format;
    }
  }
  // TODO(vikassoni): We are using below GL api calls for now as Vulkan mode
  // doesn't exist. Once we have vulkan support, we shouldn't query GL in this
  // code until we are asked to make a GL representation (or allocate a
  // backing for import into GL)? We may use an AHardwareBuffer exclusively
  // with Vulkan, where there is no need to require that a GL context is
  // current. Maybe we can lazy init this if someone tries to create an
  // AHardwareBuffer with SHARED_IMAGE_USAGE_GLES2 ||
  // !gpu_preferences.enable_vulkan. When in Vulkan mode, we should only need
  // this with GLES2.
  gl::GLApi* api = gl::g_current_gl_context;
  api->glGetIntegervFn(GL_MAX_TEXTURE_SIZE, &max_gl_texture_size_);

  // TODO(vikassoni): Check vulkan image size restrictions also.
  if (workarounds.max_texture_size) {
    max_gl_texture_size_ =
        std::min(max_gl_texture_size_, workarounds.max_texture_size);
  }
}

SharedImageBackingFactoryAHB::~SharedImageBackingFactoryAHB() = default;

std::unique_ptr<SharedImageBacking>
SharedImageBackingFactoryAHB::CreateSharedImage(
    const Mailbox& mailbox,
    viz::ResourceFormat format,
    const gfx::Size& size,
    const gfx::ColorSpace& color_space,
    uint32_t usage) {
  DCHECK(base::AndroidHardwareBufferCompat::IsSupportAvailable());

  const FormatInfo& format_info = format_info_[format];

  // Check if the format is supported by AHardwareBuffer.
  if (!format_info.ahb_supported) {
    LOG(ERROR) << "viz::ResourceFormat " << format
               << " not supported by AHardwareBuffer";
    return nullptr;
  }

  // SHARED_IMAGE_USAGE_RASTER is set when we want to write on Skia
  // representation and SHARED_IMAGE_USAGE_DISPLAY is used for cases we want
  // to read from skia representation.
  // TODO(vikassoni): Also check gpu_preferences.enable_vulkan to figure out
  // if skia is using vulkan backing or GL backing.
  const bool use_gles2 =
      (usage & (SHARED_IMAGE_USAGE_GLES2 | SHARED_IMAGE_USAGE_RASTER |
                SHARED_IMAGE_USAGE_DISPLAY));

  // If usage flags indicated this backing can be used as a GL texture, then
  // do below gl related checks.
  if (use_gles2) {
    // Check if the GL texture can be created from AHB with this format.
    if (!format_info.gl_supported) {
      LOG(ERROR)
          << "viz::ResourceFormat " << format
          << " can not be used to create a GL texture from AHardwareBuffer.";
      return nullptr;
    }
  }

  // Check if AHB can be created with the current size restrictions.
  // TODO(vikassoni): Check for VK size restrictions for VK import, GL size
  // restrictions for GL import OR both if this backing is needed to be used
  // with both GL and VK.
  if (size.width() < 1 || size.height() < 1 ||
      size.width() > max_gl_texture_size_ ||
      size.height() > max_gl_texture_size_) {
    LOG(ERROR) << "CreateSharedImage: invalid size";
    return nullptr;
  }

  // Calculate SharedImage size in bytes.
  size_t estimated_size;
  if (!viz::ResourceSizes::MaybeSizeInBytes(size, format, &estimated_size)) {
    LOG(ERROR) << "Failed to calculate SharedImage size";
    return nullptr;
  }

  // Setup AHardwareBuffer.
  AHardwareBuffer* buffer = nullptr;
  AHardwareBuffer_Desc hwb_desc;
  hwb_desc.width = size.width();
  hwb_desc.height = size.height();
  hwb_desc.format = format_info.ahb_format;

  // Set usage so that gpu can both read as a texture/write as a framebuffer
  // attachment. TODO(vikassoni): Find out if we need to set some more usage
  // flags based on the usage params in the current function call.
  hwb_desc.usage = AHARDWAREBUFFER_USAGE_GPU_SAMPLED_IMAGE |
                   AHARDWAREBUFFER_USAGE_GPU_COLOR_OUTPUT;

  // Number of images in an image array.
  hwb_desc.layers = 1;

  // The following three are not used here.
  hwb_desc.stride = 0;
  hwb_desc.rfu0 = 0;
  hwb_desc.rfu1 = 0;

  // Allocate an AHardwareBuffer.
  base::AndroidHardwareBufferCompat::GetInstance().Allocate(&hwb_desc, &buffer);
  if (!buffer) {
    LOG(ERROR) << "Failed to allocate AHardwareBuffer";
    return nullptr;
  }

  auto backing = std::make_unique<SharedImageBackingAHB>(
      mailbox, format, size, color_space, usage,
      base::android::ScopedHardwareBufferHandle::Adopt(buffer), estimated_size,
      context_state_);
  return backing;
}

std::unique_ptr<SharedImageBacking>
SharedImageBackingFactoryAHB::CreateSharedImage(
    const Mailbox& mailbox,
    viz::ResourceFormat format,
    const gfx::Size& size,
    const gfx::ColorSpace& color_space,
    uint32_t usage,
    base::span<const uint8_t> pixel_data) {
  NOTIMPLEMENTED();
  return nullptr;
}

SharedImageBackingFactoryAHB::FormatInfo::FormatInfo() = default;
SharedImageBackingFactoryAHB::FormatInfo::~FormatInfo() = default;

std::unique_ptr<SharedImageBacking>
SharedImageBackingFactoryAHB::CreateSharedImage(
    const Mailbox& mailbox,
    int client_id,
    gfx::GpuMemoryBufferHandle handle,
    gfx::BufferFormat buffer_format,
    SurfaceHandle surface_handle,
    const gfx::Size& size,
    const gfx::ColorSpace& color_space,
    uint32_t usage) {
  NOTIMPLEMENTED();
  return nullptr;
}

}  // namespace gpu