media/gpu/ipc/service/picture_buffer_manager.cc - cobalt - Git at Google

 // 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 "media/gpu/ipc/service/picture_buffer_manager.h"

 #include <map>
 #include <set>
 #include <utility>

 #include "base/bind.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/synchronization/lock.h"
 #include "base/thread_annotations.h"
 #include "components/viz/common/resources/resource_format_utils.h"
 #include "gpu/command_buffer/common/mailbox_holder.h"

 namespace media {

 namespace {

 // Generates nonnegative picture buffer IDs, which are assumed to be unique.
 int32_t NextID(int32_t* counter) {
   int32_t value = *counter;
   *counter = (*counter + 1) & 0x3FFFFFFF;
   return value;
 }

 class PictureBufferManagerImpl : public PictureBufferManager {
  public:
   explicit PictureBufferManagerImpl(
       ReusePictureBufferCB reuse_picture_buffer_cb)
       : reuse_picture_buffer_cb_(std::move(reuse_picture_buffer_cb)) {
     DVLOG(1) << __func__;
   }
   PictureBufferManagerImpl(const PictureBufferManagerImpl&) = delete;
   PictureBufferManagerImpl& operator=(const PictureBufferManagerImpl&) = delete;

   void Initialize(
       scoped_refptr<base::SingleThreadTaskRunner> gpu_task_runner,
       scoped_refptr<CommandBufferHelper> command_buffer_helper) override {
     DVLOG(1) << __func__;
     DCHECK(!gpu_task_runner_);

     gpu_task_runner_ = std::move(gpu_task_runner);
     command_buffer_helper_ = std::move(command_buffer_helper);
   }

   bool CanReadWithoutStalling() override {
     DVLOG(3) << __func__;

     base::AutoLock lock(picture_buffers_lock_);

     // If at least one picture buffer is not in use, predict that the VDA can
     // use it to output another picture.
     bool has_assigned_picture_buffer = false;
     for (const auto& it : picture_buffers_) {
       if (!it.second.dismissed) {
         // Note: If a picture buffer is waiting for SyncToken release, that
         // release is already in some command buffer (or the wait is invalid).
         // The wait will complete without further interaction from the client.
         if (it.second.output_count == 0)
           return true;
         has_assigned_picture_buffer = true;
       }
     }

     // If there are no assigned picture buffers, predict that the VDA will
     // request some.
     return !has_assigned_picture_buffer;
   }

   std::vector<PictureBuffer> CreatePictureBuffers(
       uint32_t count,
       VideoPixelFormat pixel_format,
       uint32_t planes,
       gfx::Size texture_size,
       uint32_t texture_target,
       VideoDecodeAccelerator::TextureAllocationMode mode) override {
     DVLOG(2) << __func__;
     DCHECK(gpu_task_runner_);
     DCHECK(gpu_task_runner_->BelongsToCurrentThread());
     DCHECK(count);
     DCHECK(planes);
     DCHECK_LE(planes, static_cast<uint32_t>(VideoFrame::kMaxPlanes));

     // TODO(sandersd): Consider requiring that CreatePictureBuffers() is
     // called with the context current.
     if (mode ==
         VideoDecodeAccelerator::TextureAllocationMode::kAllocateGLTextures) {
       if (!command_buffer_helper_->MakeContextCurrent()) {
         DVLOG(1) << "Failed to make context current";
         return std::vector<PictureBuffer>();
       }
     }

     std::vector<PictureBuffer> picture_buffers;
     for (uint32_t i = 0; i < count; i++) {
       PictureBufferData picture_data = {pixel_format, texture_size};
       if (mode ==
           VideoDecodeAccelerator::TextureAllocationMode::kAllocateGLTextures) {
         for (uint32_t j = 0; j < planes; j++) {
           // Use the plane size for texture-backed shared and non-shared images.
           // Adjust the size by the subsampling factor.
           const size_t width =
               VideoFrame::Columns(j, pixel_format, texture_size.width());
           const size_t height =
               VideoFrame::Rows(j, pixel_format, texture_size.height());

           picture_data.texture_sizes.emplace_back(width, height);

           // Create a texture for this plane.
           // When using shared images, the VDA might not require GL textures to
           // exist.
           // TODO(crbug.com/1011555): Do not allocate GL textures when unused.
           GLuint service_id = command_buffer_helper_->CreateTexture(
               texture_target, GL_RGBA, width, height, GL_RGBA,
               GL_UNSIGNED_BYTE);
           DCHECK(service_id);
           picture_data.service_ids.push_back(service_id);

           // The texture is not cleared yet, but it will be before the VDA
           // outputs it. Rather than requiring output to happen on the GPU
           // thread, mark the texture as cleared immediately.
           command_buffer_helper_->SetCleared(service_id);

           // Generate a mailbox while we are still on the GPU thread.
           picture_data.mailbox_holders[j] = gpu::MailboxHolder(
               command_buffer_helper_->CreateMailbox(service_id),
               gpu::SyncToken(), texture_target);
         }
       }

       // Generate a picture buffer ID and record the picture buffer.
       int32_t picture_buffer_id = NextID(&picture_buffer_id_);
       {
         base::AutoLock lock(picture_buffers_lock_);
         DCHECK(!picture_buffers_.count(picture_buffer_id));
         picture_buffers_[picture_buffer_id] = picture_data;
       }

       // Since our textures have no client IDs, we reuse the service IDs as
       // convenient unique identifiers.
       //
       // TODO(sandersd): Refactor the bind image callback to use service IDs so
       // that we can get rid of the client IDs altogether.
       picture_buffers.emplace_back(
           picture_buffer_id, texture_size, picture_data.texture_sizes,
           picture_data.service_ids, picture_data.service_ids, texture_target,
           pixel_format);
     }
     return picture_buffers;
   }

   bool DismissPictureBuffer(int32_t picture_buffer_id) override {
     DVLOG(2) << __func__ << "(" << picture_buffer_id << ")";

     base::AutoLock lock(picture_buffers_lock_);

     const auto& it = picture_buffers_.find(picture_buffer_id);
     if (it == picture_buffers_.end() || it->second.dismissed) {
       DVLOG(1) << "Unknown picture buffer " << picture_buffer_id;
       return false;
     }

     it->second.dismissed = true;

     // If the picture buffer is not in use, it should be destroyed immediately.
     if (!it->second.IsInUse()) {
       gpu_task_runner_->PostTask(
           FROM_HERE,
           base::BindOnce(&PictureBufferManagerImpl::DestroyPictureBuffer, this,
                          picture_buffer_id));
     }

     return true;
   }

   void DismissAllPictureBuffers() override {
     DVLOG(2) << __func__;

     std::vector<int32_t> assigned_picture_buffer_ids;
     {
       base::AutoLock lock(picture_buffers_lock_);

       for (const auto& it : picture_buffers_) {
         if (!it.second.dismissed)
           assigned_picture_buffer_ids.push_back(it.first);
       }
     }

     for (int32_t picture_buffer_id : assigned_picture_buffer_ids)
       DismissPictureBuffer(picture_buffer_id);
   }

   scoped_refptr<VideoFrame> CreateVideoFrame(Picture picture,
                                              base::TimeDelta timestamp,
                                              gfx::Rect visible_rect,
                                              gfx::Size natural_size) override {
     DVLOG(2) << __func__ << "(" << picture.picture_buffer_id() << ")";
     DCHECK(!picture.size_changed());
     DCHECK(!picture.texture_owner());
     DCHECK(!picture.wants_promotion_hint());

     base::AutoLock lock(picture_buffers_lock_);

     int32_t picture_buffer_id = picture.picture_buffer_id();

     // Verify that the picture buffer is available.
     const auto& it = picture_buffers_.find(picture_buffer_id);
     if (it == picture_buffers_.end() || it->second.dismissed) {
       DVLOG(1) << "Unknown picture buffer " << picture_buffer_id;
       return nullptr;
     }

     // Ensure that the picture buffer is large enough.
     PictureBufferData& picture_buffer_data = it->second;
     if (!gfx::Rect(picture_buffer_data.texture_size).Contains(visible_rect)) {
       DLOG(WARNING) << "visible_rect " << visible_rect.ToString()
                     << " exceeds coded_size "
                     << picture_buffer_data.texture_size.ToString();
       visible_rect.Intersect(gfx::Rect(picture_buffer_data.texture_size));
     }

     // Record the output.
     picture_buffer_data.output_count++;

     // If this |picture| has a SharedImage, then keep a reference to the
     // SharedImage in |picture_buffer_data| and update the gpu::MailboxHolder.
     for (int i = 0; i < VideoFrame::kMaxPlanes; i++) {
       auto image = picture.scoped_shared_image(i);
       if (image)
         picture_buffer_data.mailbox_holders[i] = image->GetMailboxHolder();
       picture_buffer_data.scoped_shared_images[i] = std::move(image);
     }

     // Create and return a VideoFrame for the picture buffer.
     scoped_refptr<VideoFrame> frame = VideoFrame::WrapNativeTextures(
         picture_buffer_data.pixel_format, picture_buffer_data.mailbox_holders,
         base::BindOnce(&PictureBufferManagerImpl::OnVideoFrameDestroyed, this,
                        picture_buffer_id),
         picture_buffer_data.texture_size, visible_rect, natural_size,
         timestamp);

     frame->set_color_space(picture.color_space());

     frame->metadata().allow_overlay = picture.allow_overlay();
     frame->metadata().read_lock_fences_enabled =
         picture.read_lock_fences_enabled();

     // TODO(sandersd): Provide an API for VDAs to control this.
     frame->metadata().power_efficient = true;

     return frame;
   }

  private:
   ~PictureBufferManagerImpl() override {
     DVLOG(1) << __func__;
     DCHECK(picture_buffers_.empty() || !command_buffer_helper_->HasStub());
   }

   void OnVideoFrameDestroyed(int32_t picture_buffer_id,
                              const gpu::SyncToken& sync_token) {
     DVLOG(3) << __func__ << "(" << picture_buffer_id << ")";

     base::AutoLock lock(picture_buffers_lock_);

     // Record the picture buffer as waiting for SyncToken release (even if it
     // has been dismissed already).
     const auto& it = picture_buffers_.find(picture_buffer_id);
     DCHECK(it != picture_buffers_.end());
     DCHECK_GT(it->second.output_count, 0);
     it->second.output_count--;
     it->second.waiting_for_synctoken_count++;

     // Wait for the SyncToken release.
     gpu_task_runner_->PostTask(
         FROM_HERE,
         base::BindOnce(
             &CommandBufferHelper::WaitForSyncToken, command_buffer_helper_,
             sync_token,
             base::BindOnce(&PictureBufferManagerImpl::OnSyncTokenReleased, this,
                            picture_buffer_id)));
   }

   void OnSyncTokenReleased(int32_t picture_buffer_id) {
     DVLOG(3) << __func__ << "(" << picture_buffer_id << ")";
     DCHECK(gpu_task_runner_);
     DCHECK(gpu_task_runner_->BelongsToCurrentThread());

     // Remove the pending wait.
     bool is_assigned = false;
     bool is_in_use = true;
     {
       base::AutoLock lock(picture_buffers_lock_);
       const auto& it = picture_buffers_.find(picture_buffer_id);
       DCHECK(it != picture_buffers_.end());

       DCHECK_GT(it->second.waiting_for_synctoken_count, 0);
       it->second.waiting_for_synctoken_count--;

       is_assigned = !it->second.dismissed;
       is_in_use = it->second.IsInUse();
     }

     // If the picture buffer is still assigned, it is ready to be reused.
     // Otherwise it should be destroyed if it is no longer in use. Neither of
     // these operations should be done while holding the lock.
     if (is_assigned) {
       // The callback is called even if the picture buffer is still in use; the
       // client is expected to wait for all copies of a picture buffer to be
       // returned before reusing any textures.
       reuse_picture_buffer_cb_.Run(picture_buffer_id);
     } else if (!is_in_use) {
       DestroyPictureBuffer(picture_buffer_id);
     }
   }

   void DestroyPictureBuffer(int32_t picture_buffer_id) {
     DVLOG(3) << __func__ << "(" << picture_buffer_id << ")";
     DCHECK(gpu_task_runner_);
     DCHECK(gpu_task_runner_->BelongsToCurrentThread());

     std::vector<GLuint> service_ids;
     std::array<scoped_refptr<Picture::ScopedSharedImage>,
                VideoFrame::kMaxPlanes>
         scoped_shared_images;
     {
       base::AutoLock lock(picture_buffers_lock_);
       const auto& it = picture_buffers_.find(picture_buffer_id);
       DCHECK(it != picture_buffers_.end());
       DCHECK(it->second.dismissed);
       DCHECK(!it->second.IsInUse());
       service_ids = std::move(it->second.service_ids);
       scoped_shared_images = std::move(it->second.scoped_shared_images);
       picture_buffers_.erase(it);
     }

     if (service_ids.empty())
       return;

     if (!command_buffer_helper_->MakeContextCurrent())
       return;

     for (GLuint service_id : service_ids)
       command_buffer_helper_->DestroyTexture(service_id);
   }

   ReusePictureBufferCB reuse_picture_buffer_cb_;

   scoped_refptr<base::SingleThreadTaskRunner> gpu_task_runner_;
   scoped_refptr<CommandBufferHelper> command_buffer_helper_;

   int32_t picture_buffer_id_ = 0;

   struct PictureBufferData {
     VideoPixelFormat pixel_format;
     gfx::Size texture_size;
     std::vector<GLuint> service_ids;
     gpu::MailboxHolder mailbox_holders[VideoFrame::kMaxPlanes];
     std::vector<gfx::Size> texture_sizes;
     std::array<scoped_refptr<Picture::ScopedSharedImage>,
                VideoFrame::kMaxPlanes>
         scoped_shared_images;
     bool dismissed = false;

     // The same picture buffer can be output from the VDA multiple times
     // concurrently, so the state is tracked using counts.
     //   |output_count|: Number of VideoFrames this picture buffer is bound to.
     //   |waiting_for_synctoken_count|: Number of returned frames that are
     //       waiting for SyncToken release.
     int output_count = 0;
     int waiting_for_synctoken_count = 0;

     bool IsInUse() const {
       return output_count > 0 || waiting_for_synctoken_count > 0;
     }
   };

   base::Lock picture_buffers_lock_;
   std::map<int32_t, PictureBufferData> picture_buffers_
       GUARDED_BY(picture_buffers_lock_);
 };

 }  // namespace

 // static
 scoped_refptr<PictureBufferManager> PictureBufferManager::Create(
     ReusePictureBufferCB reuse_picture_buffer_cb) {
   return base::MakeRefCounted<PictureBufferManagerImpl>(
       std::move(reuse_picture_buffer_cb));
 }

 }  // namespace media
	// 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 "media/gpu/ipc/service/picture_buffer_manager.h"

	#include <map>
	#include <set>
	#include <utility>

	#include "base/bind.h"
	#include "base/location.h"
	#include "base/logging.h"
	#include "base/synchronization/lock.h"
	#include "base/thread_annotations.h"
	#include "components/viz/common/resources/resource_format_utils.h"
	#include "gpu/command_buffer/common/mailbox_holder.h"

	namespace media {

	namespace {

	// Generates nonnegative picture buffer IDs, which are assumed to be unique.
	int32_t NextID(int32_t* counter) {
	int32_t value = *counter;
	counter = (counter + 1) & 0x3FFFFFFF;
	return value;
	}

	class PictureBufferManagerImpl : public PictureBufferManager {
	public:
	explicit PictureBufferManagerImpl(
	ReusePictureBufferCB reuse_picture_buffer_cb)
	: reuse_picture_buffer_cb_(std::move(reuse_picture_buffer_cb)) {
	DVLOG(1) << __func__;
	}
	PictureBufferManagerImpl(const PictureBufferManagerImpl&) = delete;
	PictureBufferManagerImpl& operator=(const PictureBufferManagerImpl&) = delete;

	void Initialize(
	scoped_refptr<base::SingleThreadTaskRunner> gpu_task_runner,
	scoped_refptr<CommandBufferHelper> command_buffer_helper) override {
	DVLOG(1) << __func__;
	DCHECK(!gpu_task_runner_);

	gpu_task_runner_ = std::move(gpu_task_runner);
	command_buffer_helper_ = std::move(command_buffer_helper);
	}

	bool CanReadWithoutStalling() override {
	DVLOG(3) << __func__;

	base::AutoLock lock(picture_buffers_lock_);

	// If at least one picture buffer is not in use, predict that the VDA can
	// use it to output another picture.
	bool has_assigned_picture_buffer = false;
	for (const auto& it : picture_buffers_) {
	if (!it.second.dismissed) {
	// Note: If a picture buffer is waiting for SyncToken release, that
	// release is already in some command buffer (or the wait is invalid).
	// The wait will complete without further interaction from the client.
	if (it.second.output_count == 0)
	return true;
	has_assigned_picture_buffer = true;
	}
	}

	// If there are no assigned picture buffers, predict that the VDA will
	// request some.
	return !has_assigned_picture_buffer;
	}

	std::vector<PictureBuffer> CreatePictureBuffers(
	uint32_t count,
	VideoPixelFormat pixel_format,
	uint32_t planes,
	gfx::Size texture_size,
	uint32_t texture_target,
	VideoDecodeAccelerator::TextureAllocationMode mode) override {
	DVLOG(2) << __func__;
	DCHECK(gpu_task_runner_);
	DCHECK(gpu_task_runner_->BelongsToCurrentThread());
	DCHECK(count);
	DCHECK(planes);
	DCHECK_LE(planes, static_cast<uint32_t>(VideoFrame::kMaxPlanes));

	// TODO(sandersd): Consider requiring that CreatePictureBuffers() is
	// called with the context current.
	if (mode ==
	VideoDecodeAccelerator::TextureAllocationMode::kAllocateGLTextures) {
	if (!command_buffer_helper_->MakeContextCurrent()) {
	DVLOG(1) << "Failed to make context current";
	return std::vector<PictureBuffer>();
	}
	}

	std::vector<PictureBuffer> picture_buffers;
	for (uint32_t i = 0; i < count; i++) {
	PictureBufferData picture_data = {pixel_format, texture_size};
	if (mode ==
	VideoDecodeAccelerator::TextureAllocationMode::kAllocateGLTextures) {
	for (uint32_t j = 0; j < planes; j++) {
	// Use the plane size for texture-backed shared and non-shared images.
	// Adjust the size by the subsampling factor.
	const size_t width =
	VideoFrame::Columns(j, pixel_format, texture_size.width());
	const size_t height =
	VideoFrame::Rows(j, pixel_format, texture_size.height());

	picture_data.texture_sizes.emplace_back(width, height);

	// Create a texture for this plane.
	// When using shared images, the VDA might not require GL textures to
	// exist.
	// TODO(crbug.com/1011555): Do not allocate GL textures when unused.
	GLuint service_id = command_buffer_helper_->CreateTexture(
	texture_target, GL_RGBA, width, height, GL_RGBA,
	GL_UNSIGNED_BYTE);
	DCHECK(service_id);
	picture_data.service_ids.push_back(service_id);

	// The texture is not cleared yet, but it will be before the VDA
	// outputs it. Rather than requiring output to happen on the GPU
	// thread, mark the texture as cleared immediately.
	command_buffer_helper_->SetCleared(service_id);

	// Generate a mailbox while we are still on the GPU thread.
	picture_data.mailbox_holders[j] = gpu::MailboxHolder(
	command_buffer_helper_->CreateMailbox(service_id),
	gpu::SyncToken(), texture_target);
	}
	}

	// Generate a picture buffer ID and record the picture buffer.
	int32_t picture_buffer_id = NextID(&picture_buffer_id_);
	{
	base::AutoLock lock(picture_buffers_lock_);
	DCHECK(!picture_buffers_.count(picture_buffer_id));
	picture_buffers_[picture_buffer_id] = picture_data;
	}

	// Since our textures have no client IDs, we reuse the service IDs as
	// convenient unique identifiers.
	//
	// TODO(sandersd): Refactor the bind image callback to use service IDs so
	// that we can get rid of the client IDs altogether.
	picture_buffers.emplace_back(
	picture_buffer_id, texture_size, picture_data.texture_sizes,
	picture_data.service_ids, picture_data.service_ids, texture_target,
	pixel_format);
	}
	return picture_buffers;
	}

	bool DismissPictureBuffer(int32_t picture_buffer_id) override {
	DVLOG(2) << __func__ << "(" << picture_buffer_id << ")";

	base::AutoLock lock(picture_buffers_lock_);

	const auto& it = picture_buffers_.find(picture_buffer_id);
	if (it == picture_buffers_.end() \|\| it->second.dismissed) {
	DVLOG(1) << "Unknown picture buffer " << picture_buffer_id;
	return false;
	}

	it->second.dismissed = true;

	// If the picture buffer is not in use, it should be destroyed immediately.
	if (!it->second.IsInUse()) {
	gpu_task_runner_->PostTask(
	FROM_HERE,
	base::BindOnce(&PictureBufferManagerImpl::DestroyPictureBuffer, this,
	picture_buffer_id));
	}

	return true;
	}

	void DismissAllPictureBuffers() override {
	DVLOG(2) << __func__;

	std::vector<int32_t> assigned_picture_buffer_ids;
	{
	base::AutoLock lock(picture_buffers_lock_);

	for (const auto& it : picture_buffers_) {
	if (!it.second.dismissed)
	assigned_picture_buffer_ids.push_back(it.first);
	}
	}

	for (int32_t picture_buffer_id : assigned_picture_buffer_ids)
	DismissPictureBuffer(picture_buffer_id);
	}

	scoped_refptr<VideoFrame> CreateVideoFrame(Picture picture,
	base::TimeDelta timestamp,
	gfx::Rect visible_rect,
	gfx::Size natural_size) override {
	DVLOG(2) << __func__ << "(" << picture.picture_buffer_id() << ")";
	DCHECK(!picture.size_changed());
	DCHECK(!picture.texture_owner());
	DCHECK(!picture.wants_promotion_hint());

	base::AutoLock lock(picture_buffers_lock_);

	int32_t picture_buffer_id = picture.picture_buffer_id();

	// Verify that the picture buffer is available.
	const auto& it = picture_buffers_.find(picture_buffer_id);
	if (it == picture_buffers_.end() \|\| it->second.dismissed) {
	DVLOG(1) << "Unknown picture buffer " << picture_buffer_id;
	return nullptr;
	}

	// Ensure that the picture buffer is large enough.
	PictureBufferData& picture_buffer_data = it->second;
	if (!gfx::Rect(picture_buffer_data.texture_size).Contains(visible_rect)) {
	DLOG(WARNING) << "visible_rect " << visible_rect.ToString()
	<< " exceeds coded_size "
	<< picture_buffer_data.texture_size.ToString();
	visible_rect.Intersect(gfx::Rect(picture_buffer_data.texture_size));
	}

	// Record the output.
	picture_buffer_data.output_count++;

	// If this \|picture\| has a SharedImage, then keep a reference to the
	// SharedImage in \|picture_buffer_data\| and update the gpu::MailboxHolder.
	for (int i = 0; i < VideoFrame::kMaxPlanes; i++) {
	auto image = picture.scoped_shared_image(i);
	if (image)
	picture_buffer_data.mailbox_holders[i] = image->GetMailboxHolder();
	picture_buffer_data.scoped_shared_images[i] = std::move(image);
	}

	// Create and return a VideoFrame for the picture buffer.
	scoped_refptr<VideoFrame> frame = VideoFrame::WrapNativeTextures(
	picture_buffer_data.pixel_format, picture_buffer_data.mailbox_holders,
	base::BindOnce(&PictureBufferManagerImpl::OnVideoFrameDestroyed, this,
	picture_buffer_id),
	picture_buffer_data.texture_size, visible_rect, natural_size,
	timestamp);

	frame->set_color_space(picture.color_space());

	frame->metadata().allow_overlay = picture.allow_overlay();
	frame->metadata().read_lock_fences_enabled =
	picture.read_lock_fences_enabled();

	// TODO(sandersd): Provide an API for VDAs to control this.
	frame->metadata().power_efficient = true;

	return frame;
	}

	private:
	~PictureBufferManagerImpl() override {
	DVLOG(1) << __func__;
	DCHECK(picture_buffers_.empty() \|\| !command_buffer_helper_->HasStub());
	}

	void OnVideoFrameDestroyed(int32_t picture_buffer_id,
	const gpu::SyncToken& sync_token) {
	DVLOG(3) << __func__ << "(" << picture_buffer_id << ")";

	base::AutoLock lock(picture_buffers_lock_);

	// Record the picture buffer as waiting for SyncToken release (even if it
	// has been dismissed already).
	const auto& it = picture_buffers_.find(picture_buffer_id);
	DCHECK(it != picture_buffers_.end());
	DCHECK_GT(it->second.output_count, 0);
	it->second.output_count--;
	it->second.waiting_for_synctoken_count++;

	// Wait for the SyncToken release.
	gpu_task_runner_->PostTask(
	FROM_HERE,
	base::BindOnce(
	&CommandBufferHelper::WaitForSyncToken, command_buffer_helper_,
	sync_token,
	base::BindOnce(&PictureBufferManagerImpl::OnSyncTokenReleased, this,
	picture_buffer_id)));
	}

	void OnSyncTokenReleased(int32_t picture_buffer_id) {
	DVLOG(3) << __func__ << "(" << picture_buffer_id << ")";
	DCHECK(gpu_task_runner_);
	DCHECK(gpu_task_runner_->BelongsToCurrentThread());

	// Remove the pending wait.
	bool is_assigned = false;
	bool is_in_use = true;
	{
	base::AutoLock lock(picture_buffers_lock_);
	const auto& it = picture_buffers_.find(picture_buffer_id);
	DCHECK(it != picture_buffers_.end());

	DCHECK_GT(it->second.waiting_for_synctoken_count, 0);
	it->second.waiting_for_synctoken_count--;

	is_assigned = !it->second.dismissed;
	is_in_use = it->second.IsInUse();
	}

	// If the picture buffer is still assigned, it is ready to be reused.
	// Otherwise it should be destroyed if it is no longer in use. Neither of
	// these operations should be done while holding the lock.
	if (is_assigned) {
	// The callback is called even if the picture buffer is still in use; the
	// client is expected to wait for all copies of a picture buffer to be
	// returned before reusing any textures.
	reuse_picture_buffer_cb_.Run(picture_buffer_id);
	} else if (!is_in_use) {
	DestroyPictureBuffer(picture_buffer_id);
	}
	}

	void DestroyPictureBuffer(int32_t picture_buffer_id) {
	DVLOG(3) << __func__ << "(" << picture_buffer_id << ")";
	DCHECK(gpu_task_runner_);
	DCHECK(gpu_task_runner_->BelongsToCurrentThread());

	std::vector<GLuint> service_ids;
	std::array<scoped_refptr<Picture::ScopedSharedImage>,
	VideoFrame::kMaxPlanes>
	scoped_shared_images;
	{
	base::AutoLock lock(picture_buffers_lock_);
	const auto& it = picture_buffers_.find(picture_buffer_id);
	DCHECK(it != picture_buffers_.end());
	DCHECK(it->second.dismissed);
	DCHECK(!it->second.IsInUse());
	service_ids = std::move(it->second.service_ids);
	scoped_shared_images = std::move(it->second.scoped_shared_images);
	picture_buffers_.erase(it);
	}

	if (service_ids.empty())
	return;

	if (!command_buffer_helper_->MakeContextCurrent())
	return;

	for (GLuint service_id : service_ids)
	command_buffer_helper_->DestroyTexture(service_id);
	}

	ReusePictureBufferCB reuse_picture_buffer_cb_;

	scoped_refptr<base::SingleThreadTaskRunner> gpu_task_runner_;
	scoped_refptr<CommandBufferHelper> command_buffer_helper_;

	int32_t picture_buffer_id_ = 0;

	struct PictureBufferData {
	VideoPixelFormat pixel_format;
	gfx::Size texture_size;
	std::vector<GLuint> service_ids;
	gpu::MailboxHolder mailbox_holders[VideoFrame::kMaxPlanes];
	std::vector<gfx::Size> texture_sizes;
	std::array<scoped_refptr<Picture::ScopedSharedImage>,
	VideoFrame::kMaxPlanes>
	scoped_shared_images;
	bool dismissed = false;

	// The same picture buffer can be output from the VDA multiple times
	// concurrently, so the state is tracked using counts.
	// \|output_count\|: Number of VideoFrames this picture buffer is bound to.
	// \|waiting_for_synctoken_count\|: Number of returned frames that are
	// waiting for SyncToken release.
	int output_count = 0;
	int waiting_for_synctoken_count = 0;

	bool IsInUse() const {
	return output_count > 0 \|\| waiting_for_synctoken_count > 0;
	}
	};

	base::Lock picture_buffers_lock_;
	std::map<int32_t, PictureBufferData> picture_buffers_
	GUARDED_BY(picture_buffers_lock_);
	};

	} // namespace

	// static
	scoped_refptr<PictureBufferManager> PictureBufferManager::Create(
	ReusePictureBufferCB reuse_picture_buffer_cb) {
	return base::MakeRefCounted<PictureBufferManagerImpl>(
	std::move(reuse_picture_buffer_cb));
	}

	} // namespace media