GLInProcessContext: support async flushes and dedicated GPU thread

gpu/command_buffer/service/in_process_command_buffer.cc

Index: gpu/command_buffer/service/in_process_command_buffer.cc
diff --git a/gpu/command_buffer/service/in_process_command_buffer.cc b/gpu/command_buffer/service/in_process_command_buffer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..2bd18ea29f55b187000b253aee7eb10d6e72c665
--- /dev/null
+++ b/gpu/command_buffer/service/in_process_command_buffer.cc
@@ -0,0 +1,703 @@
+// 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 "gpu/command_buffer/service/in_process_command_buffer.h"
+
+#include <queue>
+#include <utility>
+
+#include <GLES2/gl2.h>
+#ifndef GL_GLEXT_PROTOTYPES
+#define GL_GLEXT_PROTOTYPES 1
+#endif
+#include <GLES2/gl2ext.h>
+#include <GLES2/gl2extchromium.h>
+
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/lazy_instance.h"
+#include "base/logging.h"
+#include "base/memory/weak_ptr.h"
+#include "base/message_loop/message_loop_proxy.h"
+#include "base/threading/thread.h"
+#include "gpu/command_buffer/common/id_allocator.h"
+#include "gpu/command_buffer/service/command_buffer_service.h"
+#include "gpu/command_buffer/service/context_group.h"
+#include "gpu/command_buffer/service/gl_context_virtual.h"
+#include "gpu/command_buffer/service/gpu_scheduler.h"
+#include "gpu/command_buffer/service/image_manager.h"
+#include "gpu/command_buffer/service/transfer_buffer_manager.h"
+#include "ui/gfx/size.h"
+#include "ui/gl/gl_context.h"
+#include "ui/gl/gl_image.h"
+#include "ui/gl/gl_share_group.h"
+#include "ui/gl/gl_surface.h"
+
+namespace gpu {
+
+namespace {
+
+static base::LazyInstance<std::set<InProcessCommandBuffer*> >
+    g_all_shared_contexts = LAZY_INSTANCE_INITIALIZER;
+
+static bool g_use_virtualized_gl_context = false;
+static bool g_uses_explicit_scheduling = false;
+
+template <typename T>
+static void RunTaskWithResult(base::Callback<T(void)> task,
+                              T* result,
+                              base::WaitableEvent* completion) {
+  *result = task.Run();
+  completion->Signal();
+}
+
+class GpuInProcessThread
+    : public base::Thread,
+      public base::RefCountedThreadSafe<GpuInProcessThread> {
+ public:
+  GpuInProcessThread();
+
+ private:
+  friend class base::RefCountedThreadSafe<GpuInProcessThread>;
+  virtual ~GpuInProcessThread();
+
+  DISALLOW_COPY_AND_ASSIGN(GpuInProcessThread);
+};
+
+GpuInProcessThread::GpuInProcessThread() : base::Thread("GpuThread") {
+  Start();
+}
+
+GpuInProcessThread::~GpuInProcessThread() {
+  Stop();
+}
+
+// Used with explicit scheduling when there is no dedicated GPU thread.
+class GpuCommandQueue {
+ public:
+  GpuCommandQueue();
+  ~GpuCommandQueue();
+
+  void QueueTask(const base::Closure& task);
+  void RunTasks();
+  void SetScheduleCallback(const base::Closure& callback);
+
+ private:
+  base::Lock tasks_lock_;
+  std::queue<base::Closure> tasks_;
+  base::Closure schedule_callback_;
+
+  DISALLOW_COPY_AND_ASSIGN(GpuCommandQueue);
+};
+
+GpuCommandQueue::GpuCommandQueue() {}
+
+GpuCommandQueue::~GpuCommandQueue() {
+  base::AutoLock lock(tasks_lock_);
+  DCHECK(tasks_.empty());
+}
+
+void GpuCommandQueue::QueueTask(const base::Closure& task) {
+  {
+    base::AutoLock lock(tasks_lock_);
+    tasks_.push(task);
+  }
+
+  DCHECK(!schedule_callback_.is_null());
+  schedule_callback_.Run();
+}
+
+void GpuCommandQueue::RunTasks() {
+  size_t num_tasks;
+  {
+    base::AutoLock lock(tasks_lock_);
+    num_tasks = tasks_.size();
+  }
+
+  while (num_tasks) {
+    base::Closure task;
+    {
+      base::AutoLock lock(tasks_lock_);
+      task = tasks_.front();
+      tasks_.pop();
+      num_tasks = tasks_.size();
+    }
+
+    task.Run();
+  }
+}
+
+void GpuCommandQueue::SetScheduleCallback(const base::Closure& callback) {
+  DCHECK(schedule_callback_.is_null());
+  schedule_callback_ = callback;
+}
+
+static base::LazyInstance<GpuCommandQueue> g_gpu_queue =
+    LAZY_INSTANCE_INITIALIZER;
+
+class SchedulerClientBase : public InProcessCommandBuffer::SchedulerClient {
+ public:
+  explicit SchedulerClientBase(bool need_thread);
+  virtual ~SchedulerClientBase();
+
+  static bool HasClients();
+
+ protected:
+  scoped_refptr<GpuInProcessThread> thread_;
+
+ private:
+  static base::LazyInstance<std::set<SchedulerClientBase*> > all_clients_;
+  static base::LazyInstance<base::Lock> all_clients_lock_;
+};
+
+base::LazyInstance<std::set<SchedulerClientBase*> >
+    SchedulerClientBase::all_clients_ = LAZY_INSTANCE_INITIALIZER;
+base::LazyInstance<base::Lock> SchedulerClientBase::all_clients_lock_ =
+    LAZY_INSTANCE_INITIALIZER;
+
+SchedulerClientBase::SchedulerClientBase(bool need_thread) {
+  base::AutoLock(all_clients_lock_.Get());
+  if (need_thread) {
+    if (!all_clients_.Get().empty()) {
+      SchedulerClientBase* other = *all_clients_.Get().begin();
+      thread_ = other->thread_;
+      DCHECK(thread_.get());
+    } else {
+      thread_ = new GpuInProcessThread;
+    }
+  }
+  all_clients_.Get().insert(this);
+}
+
+SchedulerClientBase::~SchedulerClientBase() {
+  base::AutoLock(all_clients_lock_.Get());
+  all_clients_.Get().erase(this);
+}
+
+bool SchedulerClientBase::HasClients() {
+  base::AutoLock(all_clients_lock_.Get());
+  return !all_clients_.Get().empty();
+}
+
+// A client that talks to the GPU thread
+class ThreadClient : public SchedulerClientBase {
+ public:
+  ThreadClient();
+  virtual void QueueTask(const base::Closure& task) OVERRIDE;
+};
+
+ThreadClient::ThreadClient() : SchedulerClientBase(true) {
+  DCHECK(thread_.get());
+}
+
+void ThreadClient::QueueTask(const base::Closure& task) {
+  thread_->message_loop()->PostTask(FROM_HERE, task);
+}
+
+// A client that talks to the GpuCommandQueue
+class QueueClient : public SchedulerClientBase {
+ public:
+  QueueClient();
+  virtual void QueueTask(const base::Closure& task) OVERRIDE;
+};
+
+QueueClient::QueueClient() : SchedulerClientBase(false) {
+  DCHECK(!thread_.get());
+}
+
+void QueueClient::QueueTask(const base::Closure& task) {
+  g_gpu_queue.Get().QueueTask(task);
+}
+
+static scoped_ptr<InProcessCommandBuffer::SchedulerClient>
+CreateSchedulerClient() {
+  scoped_ptr<InProcessCommandBuffer::SchedulerClient> client;
+  if (g_uses_explicit_scheduling)
+    client.reset(new QueueClient);
+  else
+    client.reset(new ThreadClient);
+
+  return client.Pass();
+}
+
+class ScopedEvent {
+ public:
+  ScopedEvent(base::WaitableEvent* event) : event_(event) {}
+  ~ScopedEvent() { event_->Signal(); }
+
+ private:
+  base::WaitableEvent* event_;
+};
+
+}  // anonyous namespace
+
+InProcessCommandBuffer::InProcessCommandBuffer()
+    : context_lost_(false),
+      share_group_id_(0),
+      last_put_offset_(-1),
+      flush_event_(false, false),
+      queue_(CreateSchedulerClient()) {}
+
+InProcessCommandBuffer::~InProcessCommandBuffer() {
+  Destroy();
+}
+
+bool InProcessCommandBuffer::IsContextLost() {
+  if (context_lost_ || !command_buffer_) {
+    return true;
+  }
+  CommandBuffer::State state = GetState();
+  return error::IsError(state.error);
+}
+
+void InProcessCommandBuffer::OnResizeView(gfx::Size size, float scale_factor) {
+  DCHECK(!surface_->IsOffscreen());
+  surface_->Resize(size);
+}
+
+bool InProcessCommandBuffer::MakeCurrent() {
+  command_buffer_lock_.AssertAcquired();
+
+  if (!context_lost_ && decoder_->MakeCurrent())
+    return true;
+  DLOG(ERROR) << "Context lost because MakeCurrent failed.";
+  command_buffer_->SetContextLostReason(decoder_->GetContextLostReason());
+  command_buffer_->SetParseError(gpu::error::kLostContext);
+  return false;
+}
+
+void InProcessCommandBuffer::PumpCommands() {
+  ScopedEvent handle_flush(&flush_event_);
+  command_buffer_lock_.AssertAcquired();
+
+  if (!MakeCurrent())
+    return;
+
+  gpu_scheduler_->PutChanged();
+  CommandBuffer::State state = command_buffer_->GetState();
+  DCHECK((!error::IsError(state.error) && !context_lost_) ||
+         (error::IsError(state.error) && context_lost_));
+}
+
+bool InProcessCommandBuffer::GetBufferChanged(int32 transfer_buffer_id) {
+  command_buffer_lock_.AssertAcquired();
+  command_buffer_->SetGetBuffer(transfer_buffer_id);
+  return true;
+}
+
+bool InProcessCommandBuffer::Initialize(
+    bool is_offscreen,
+    bool share_resources,
+    gfx::AcceleratedWidget window,
+    const gfx::Size& size,
+    const char* allowed_extensions,
+    const std::vector<int32>& attribs,
+    gfx::GpuPreference gpu_preference,
+    const base::Closure& context_lost_callback,
+    unsigned int share_group_id) {
+
+  share_resources_ = share_resources;
+  context_lost_callback_ = WrapCallback(context_lost_callback);
+  share_group_id_ = share_group_id;
+
+  base::WaitableEvent completion(true, false);
+  bool result;
+  base::Callback<bool(void)> init_task =
+      base::Bind(&InProcessCommandBuffer::InitializeOnGpuThread,
+                 base::Unretained(this),
+                 is_offscreen,
+                 window,
+                 size,
+                 allowed_extensions,
+                 attribs,
+                 gpu_preference);
+  QueueTask(
+      base::Bind(&RunTaskWithResult<bool>, init_task, &result, &completion));
+  completion.Wait();

[vignatti (out of this project), 2013/08/05 13:54:09]

Hi. I'm not sure if content_shell through the use of in-process command buffer
is in your mind, but Wait() is not allowed on such context; DisallowWaiting() is
being called during BrowserMainLoop::PreMainMessageLoopRun. I haven't thought
either about another way to wait the end of the InitializeOnGpuThread()
execution...

+  return result;
+}
+
+bool InProcessCommandBuffer::InitializeOnGpuThread(
+    bool is_offscreen,
+    gfx::AcceleratedWidget window,
+    const gfx::Size& size,
+    const char* allowed_extensions,
+    const std::vector<int32>& attribs,
+    gfx::GpuPreference gpu_preference) {
+  // Use one share group for all contexts.
+  CR_DEFINE_STATIC_LOCAL(scoped_refptr<gfx::GLShareGroup>, share_group,
+                         (new gfx::GLShareGroup));
+
+  DCHECK(size.width() >= 0 && size.height() >= 0);
+
+  TransferBufferManager* manager = new TransferBufferManager();
+  transfer_buffer_manager_.reset(manager);
+  manager->Initialize();
+
+  scoped_ptr<CommandBufferService> command_buffer(
+      new CommandBufferService(transfer_buffer_manager_.get()));
+  command_buffer->SetPutOffsetChangeCallback(base::Bind(
+      &InProcessCommandBuffer::PumpCommands, base::Unretained(this)));
+  command_buffer->SetParseErrorCallback(base::Bind(
+      &InProcessCommandBuffer::OnContextLost, base::Unretained(this)));
+
+  if (!command_buffer->Initialize()) {
+    LOG(ERROR) << "Could not initialize command buffer.";
+    DestroyOnGpuThread();
+    return false;
+  }
+
+  InProcessCommandBuffer* context_group = NULL;
+
+  if (share_resources_ && !g_all_shared_contexts.Get().empty()) {
+    DCHECK(share_group_id_);
+    for (std::set<InProcessCommandBuffer*>::iterator it =
+             g_all_shared_contexts.Get().begin();
+         it != g_all_shared_contexts.Get().end();
+         ++it) {
+      if ((*it)->share_group_id_ == share_group_id_) {
+        context_group = *it;
+        DCHECK(context_group->share_resources_);
+        context_lost_ = context_group->IsContextLost();
+        break;
+      }
+    }
+    if (!context_group)
+      share_group = new gfx::GLShareGroup;
+  }
+
+  bool bind_generates_resource = false;
+  decoder_.reset(gles2::GLES2Decoder::Create(
+      context_group ? context_group->decoder_->GetContextGroup()
+                    : new gles2::ContextGroup(
+                          NULL, NULL, NULL, NULL, bind_generates_resource)));
+
+  gpu_scheduler_.reset(
+      new GpuScheduler(command_buffer.get(), decoder_.get(), decoder_.get()));
+  command_buffer->SetGetBufferChangeCallback(base::Bind(
+      &GpuScheduler::SetGetBuffer, base::Unretained(gpu_scheduler_.get())));
+  command_buffer_ = command_buffer.Pass();
+
+  decoder_->set_engine(gpu_scheduler_.get());
+
+  if (is_offscreen)
+    surface_ = gfx::GLSurface::CreateOffscreenGLSurface(size);
+  else
+    surface_ = gfx::GLSurface::CreateViewGLSurface(window);
+
+  if (!surface_.get()) {
+    LOG(ERROR) << "Could not create GLSurface.";
+    DestroyOnGpuThread();
+    return false;
+  }
+
+  if (g_use_virtualized_gl_context) {
+    context_ = share_group->GetSharedContext();
+    if (!context_.get()) {
+      context_ = gfx::GLContext::CreateGLContext(
+          share_group.get(), surface_.get(), gpu_preference);
+      share_group->SetSharedContext(context_.get());
+    }
+
+    context_ = new GLContextVirtual(
+        share_group.get(), context_.get(), decoder_->AsWeakPtr());
+    if (context_->Initialize(surface_.get(), gpu_preference)) {
+      VLOG(1) << "Created virtual GL context.";
+    } else {
+      context_ = NULL;
+    }
+  } else {
+    context_ = gfx::GLContext::CreateGLContext(
+        share_group.get(), surface_.get(), gpu_preference);
+  }
+
+  if (!context_.get()) {
+    LOG(ERROR) << "Could not create GLContext.";
+    DestroyOnGpuThread();
+    return false;
+  }
+
+  if (!context_->MakeCurrent(surface_.get())) {
+    LOG(ERROR) << "Could not make context current.";
+    DestroyOnGpuThread();
+    return false;
+  }
+
+  gles2::DisallowedFeatures disallowed_features;
+  disallowed_features.swap_buffer_complete_callback = true;
+  disallowed_features.gpu_memory_manager = true;
+  if (!decoder_->Initialize(surface_,
+                            context_,
+                            is_offscreen,
+                            size,
+                            disallowed_features,
+                            allowed_extensions,
+                            attribs)) {
+    LOG(ERROR) << "Could not initialize decoder.";
+    DestroyOnGpuThread();
+    return false;
+  }
+
+  if (!is_offscreen) {
+    decoder_->SetResizeCallback(base::Bind(
+        &InProcessCommandBuffer::OnResizeView, base::Unretained(this)));
+  }
+
+  if (share_resources_) {
+    g_all_shared_contexts.Pointer()->insert(this);
+  }
+
+  return true;
+}
+
+void InProcessCommandBuffer::Destroy() {
+  base::WaitableEvent completion(true, false);
+  bool result;
+  base::Callback<bool(void)> destroy_task = base::Bind(
+      &InProcessCommandBuffer::DestroyOnGpuThread, base::Unretained(this));
+  QueueTask(
+      base::Bind(&RunTaskWithResult<bool>, destroy_task, &result, &completion));
+  completion.Wait();
+}
+
+bool InProcessCommandBuffer::DestroyOnGpuThread() {
+  command_buffer_.reset();
+  // Clean up GL resources if possible.
+  bool have_context = context_ && context_->MakeCurrent(surface_);
+  if (decoder_) {
+    decoder_->Destroy(have_context);
+    decoder_.reset();
+  }
+  context_ = NULL;
+  surface_ = NULL;
+
+  g_all_shared_contexts.Pointer()->erase(this);
+  return true;
+}
+
+unsigned int InProcessCommandBuffer::CreateImageForGpuMemoryBuffer(
+    gfx::GpuMemoryBufferHandle buffer,
+    gfx::Size size) {
+  unsigned int image_id;
+  {
+    // TODO: ID allocation should go through CommandBuffer
+    base::AutoLock lock(command_buffer_lock_);
+    gles2::ContextGroup* group = decoder_->GetContextGroup();
+    image_id =
+        group->GetIdAllocator(gles2::id_namespaces::kImages)->AllocateID();
+  }
+  base::Closure image_task =
+      base::Bind(&InProcessCommandBuffer::CreateImageOnGpuThread,
+                 base::Unretained(this), buffer, size, image_id);
+  QueueTask(image_task);
+  return image_id;
+}
+
+void InProcessCommandBuffer::CreateImageOnGpuThread(
+    gfx::GpuMemoryBufferHandle buffer,
+    gfx::Size size,
+    unsigned int image_id) {
+  scoped_refptr<gfx::GLImage> gl_image =
+      gfx::GLImage::CreateGLImageForGpuMemoryBuffer(buffer, size);
+   decoder_->GetContextGroup()->image_manager()->AddImage(gl_image, image_id);
+}
+
+void InProcessCommandBuffer::RemoveImage(unsigned int image_id) {
+  {
+    // TODO: ID allocation should go through CommandBuffer
+    base::AutoLock lock(command_buffer_lock_);
+    gles2::ContextGroup* group = decoder_->GetContextGroup();
+    group->GetIdAllocator(gles2::id_namespaces::kImages)->FreeID(image_id);
+  }
+  base::Closure image_manager_task =
+      base::Bind(&InProcessCommandBuffer::RemoveImageOnGpuThread,
+                 base::Unretained(this),
+                 image_id);
+  QueueTask(image_manager_task);
+}
+
+void InProcessCommandBuffer::RemoveImageOnGpuThread(unsigned int image_id) {
+  decoder_->GetContextGroup()->image_manager()->RemoveImage(image_id);
+}
+
+void InProcessCommandBuffer::OnContextLost() {
+  if (!context_lost_callback_.is_null()) {
+    context_lost_callback_.Run();
+    context_lost_callback_.Reset();
+  }
+
+  context_lost_ = true;
+  if (share_resources_) {
+    for (std::set<InProcessCommandBuffer*>::iterator it =
+             g_all_shared_contexts.Get().begin();
+         it != g_all_shared_contexts.Get().end();
+         ++it) {
+      (*it)->context_lost_ = true;
+    }
+  }
+}
+
+CommandBuffer::State InProcessCommandBuffer::GetStateFast() {
+  base::AutoLock lock(command_buffer_lock_);
+  return last_state_ = command_buffer_->GetState();
+}
+
+CommandBuffer::State InProcessCommandBuffer::GetState() {
+  return GetStateFast();
+}
+
+CommandBuffer::State InProcessCommandBuffer::GetLastState() {
+  return last_state_;
+}
+
+int32 InProcessCommandBuffer::GetLastToken() { return last_state_.token; }
+
+void InProcessCommandBuffer::FlushOnGpuThread(int32 put_offset) {
+  base::AutoLock lock(command_buffer_lock_);
+  command_buffer_->Flush(put_offset);
+}
+
+void InProcessCommandBuffer::Flush(int32 put_offset) {
+  if (last_state_.error != gpu::error::kNoError)
+    return;
+
+  if (last_put_offset_ == put_offset)
+    return;
+
+  last_put_offset_ = put_offset;
+  base::Closure task = base::Bind(&InProcessCommandBuffer::FlushOnGpuThread,
+                                  base::Unretained(this),
+                                  put_offset);
+  QueueTask(task);
+}
+
+CommandBuffer::State InProcessCommandBuffer::FlushSync(int32 put_offset,
+                                                       int32 last_known_get) {
+  if (put_offset == last_known_get || last_state_.error != gpu::error::kNoError)
+    return last_state_;
+
+  Flush(put_offset);
+  GetStateFast();
+  while (last_known_get == last_state_.get_offset &&
+         last_state_.error == gpu::error::kNoError) {
+    flush_event_.Wait();
+    GetStateFast();
+  }
+
+  return last_state_;
+}
+
+void InProcessCommandBuffer::SetGetBuffer(int32 shm_id) {
+  if (last_state_.error != gpu::error::kNoError)
+    return;
+
+  {
+    base::AutoLock lock(command_buffer_lock_);
+    command_buffer_->SetGetBuffer(shm_id);
+    last_put_offset_ = 0;
+  }
+  GetStateFast();
+}
+
+gpu::Buffer InProcessCommandBuffer::CreateTransferBuffer(size_t size,
+                                                         int32* id) {
+  base::AutoLock lock(command_buffer_lock_);
+  return command_buffer_->CreateTransferBuffer(size, id);
+}
+
+void InProcessCommandBuffer::DestroyTransferBuffer(int32 id) {
+  base::Closure task = base::Bind(&CommandBuffer::DestroyTransferBuffer,
+                                  base::Unretained(command_buffer_.get()),
+                                  id);
+
+  QueueTask(task);
+}
+
+gpu::Buffer InProcessCommandBuffer::GetTransferBuffer(int32 id) {
+  NOTREACHED();
+  return gpu::Buffer();
+}
+
+uint32 InProcessCommandBuffer::InsertSyncPoint() {
+  NOTREACHED();
+  return 0;
+}
+void InProcessCommandBuffer::SignalSyncPoint(unsigned sync_point,
+                                             const base::Closure& callback) {
+  QueueTask(WrapCallback(callback));
+}
+
+gpu::error::Error InProcessCommandBuffer::GetLastError() {
+  return last_state_.error;
+}
+
+bool InProcessCommandBuffer::Initialize() {
+  NOTREACHED();
+  return false;
+}
+
+void InProcessCommandBuffer::SetGetOffset(int32 get_offset) { NOTREACHED(); }
+
+void InProcessCommandBuffer::SetToken(int32 token) { NOTREACHED(); }
+
+void InProcessCommandBuffer::SetParseError(gpu::error::Error error) {
+  NOTREACHED();
+}
+
+void InProcessCommandBuffer::SetContextLostReason(
+    gpu::error::ContextLostReason reason) {
+  NOTREACHED();
+}
+
+namespace {
+
+void PostCallback(const scoped_refptr<base::MessageLoopProxy>& loop,
+                         const base::Closure& callback) {
+  if (!loop->BelongsToCurrentThread()) {
+    loop->PostTask(FROM_HERE, callback);
+  } else {
+    callback.Run();
+  }
+}
+
+void RunOnTargetThread(scoped_ptr<base::Closure> callback) {
+  DCHECK(callback.get());
+  callback->Run();
+}
+
+}  // anonymous namespace
+
+base::Closure InProcessCommandBuffer::WrapCallback(
+    const base::Closure& callback) {
+  // Make sure the callback gets deleted on the target thread by passing
+  // ownership.
+  scoped_ptr<base::Closure> scoped_callback(new base::Closure(callback));
+  base::Closure callback_on_client_thread =
+      base::Bind(&RunOnTargetThread, base::Passed(&scoped_callback));
+  base::Closure wrapped_callback =
+      base::Bind(&PostCallback, base::MessageLoopProxy::current(),
+                 callback_on_client_thread);
+  return wrapped_callback;
+}
+
+// static
+void InProcessCommandBuffer::EnableVirtualizedContext() {
+  g_use_virtualized_gl_context = true;
+}
+
+// static
+void InProcessCommandBuffer::SetScheduleCallback(
+    const base::Closure& callback) {
+  DCHECK(!g_uses_explicit_scheduling);
+  DCHECK(!SchedulerClientBase::HasClients());
+  g_uses_explicit_scheduling = true;
+  g_gpu_queue.Get().SetScheduleCallback(callback);
+}
+
+// static
+void InProcessCommandBuffer::ProcessGpuWorkOnCurrentThread() {
+  g_gpu_queue.Get().RunTasks();
+}
+
+}  // namespace gpu