cc/trees/single_thread_proxy.cc - chromium/src - Git at Google

 // Copyright 2011 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 "cc/trees/single_thread_proxy.h"

 #include "base/auto_reset.h"
 #include "base/debug/trace_event.h"
 #include "cc/debug/benchmark_instrumentation.h"
 #include "cc/output/context_provider.h"
 #include "cc/output/output_surface.h"
 #include "cc/quads/draw_quad.h"
 #include "cc/resources/prioritized_resource_manager.h"
 #include "cc/resources/resource_update_controller.h"
 #include "cc/trees/blocking_task_runner.h"
 #include "cc/trees/layer_tree_host.h"
 #include "cc/trees/layer_tree_host_single_thread_client.h"
 #include "cc/trees/layer_tree_impl.h"
 #include "cc/trees/scoped_abort_remaining_swap_promises.h"
 #include "ui/gfx/frame_time.h"

 namespace cc {

 scoped_ptr<Proxy> SingleThreadProxy::Create(
     LayerTreeHost* layer_tree_host,
     LayerTreeHostSingleThreadClient* client,
     scoped_refptr<base::SingleThreadTaskRunner> main_task_runner) {
   return make_scoped_ptr(
              new SingleThreadProxy(layer_tree_host, client, main_task_runner))
       .PassAs<Proxy>();
 }

 SingleThreadProxy::SingleThreadProxy(
     LayerTreeHost* layer_tree_host,
     LayerTreeHostSingleThreadClient* client,
     scoped_refptr<base::SingleThreadTaskRunner> main_task_runner)
     : Proxy(main_task_runner, NULL),
       layer_tree_host_(layer_tree_host),
       client_(client),
       timing_history_(layer_tree_host->rendering_stats_instrumentation()),
       next_frame_is_newly_committed_frame_(false),
       inside_draw_(false),
       defer_commits_(false),
       commit_was_deferred_(false),
       commit_requested_(false),
       weak_factory_(this) {
   TRACE_EVENT0("cc", "SingleThreadProxy::SingleThreadProxy");
   DCHECK(Proxy::IsMainThread());
   DCHECK(layer_tree_host);

   // Impl-side painting not supported without threaded compositing.
   CHECK(!layer_tree_host->settings().impl_side_painting)
       << "Threaded compositing must be enabled to use impl-side painting.";
 }

 void SingleThreadProxy::Start() {
   DebugScopedSetImplThread impl(this);
   layer_tree_host_impl_ = layer_tree_host_->CreateLayerTreeHostImpl(this);
 }

 SingleThreadProxy::~SingleThreadProxy() {
   TRACE_EVENT0("cc", "SingleThreadProxy::~SingleThreadProxy");
   DCHECK(Proxy::IsMainThread());
   // Make sure Stop() got called or never Started.
   DCHECK(!layer_tree_host_impl_);
 }

 void SingleThreadProxy::FinishAllRendering() {
   TRACE_EVENT0("cc", "SingleThreadProxy::FinishAllRendering");
   DCHECK(Proxy::IsMainThread());
   {
     DebugScopedSetImplThread impl(this);
     layer_tree_host_impl_->FinishAllRendering();
   }
 }

 bool SingleThreadProxy::IsStarted() const {
   DCHECK(Proxy::IsMainThread());
   return layer_tree_host_impl_;
 }

 void SingleThreadProxy::SetLayerTreeHostClientReady() {
   TRACE_EVENT0("cc", "SingleThreadProxy::SetLayerTreeHostClientReady");
   // Scheduling is controlled by the embedder in the single thread case, so
   // nothing to do.
   DCHECK(Proxy::IsMainThread());
   DebugScopedSetImplThread impl(this);
   if (layer_tree_host_->settings().single_thread_proxy_scheduler &&
       !scheduler_on_impl_thread_) {
     SchedulerSettings scheduler_settings(layer_tree_host_->settings());
     scheduler_on_impl_thread_ = Scheduler::Create(this,
                                                   scheduler_settings,
                                                   layer_tree_host_->id(),
                                                   MainThreadTaskRunner());
     scheduler_on_impl_thread_->SetCanStart();
     scheduler_on_impl_thread_->SetVisible(layer_tree_host_impl_->visible());
   }
 }

 void SingleThreadProxy::SetVisible(bool visible) {
   TRACE_EVENT0("cc", "SingleThreadProxy::SetVisible");
   DebugScopedSetImplThread impl(this);
   layer_tree_host_impl_->SetVisible(visible);
   if (scheduler_on_impl_thread_)
     scheduler_on_impl_thread_->SetVisible(layer_tree_host_impl_->visible());
   // Changing visibility could change ShouldComposite().
   UpdateBackgroundAnimateTicking();
 }

 void SingleThreadProxy::CreateAndInitializeOutputSurface() {
   TRACE_EVENT0(
       "cc", "SingleThreadProxy::CreateAndInitializeOutputSurface");
   DCHECK(Proxy::IsMainThread());
   DCHECK(layer_tree_host_->output_surface_lost());

   scoped_ptr<OutputSurface> output_surface =
       layer_tree_host_->CreateOutputSurface();

   renderer_capabilities_for_main_thread_ = RendererCapabilities();

   bool success = !!output_surface;
   if (success) {
     DebugScopedSetMainThreadBlocked main_thread_blocked(this);
     DebugScopedSetImplThread impl(this);
     layer_tree_host_->DeleteContentsTexturesOnImplThread(
         layer_tree_host_impl_->resource_provider());
     success = layer_tree_host_impl_->InitializeRenderer(output_surface.Pass());
   }

   layer_tree_host_->OnCreateAndInitializeOutputSurfaceAttempted(success);

   if (success) {
     if (scheduler_on_impl_thread_)
       scheduler_on_impl_thread_->DidCreateAndInitializeOutputSurface();
   } else if (Proxy::MainThreadTaskRunner()) {
     MainThreadTaskRunner()->PostTask(
         FROM_HERE,
         base::Bind(&SingleThreadProxy::CreateAndInitializeOutputSurface,
                    weak_factory_.GetWeakPtr()));
   }
 }

 const RendererCapabilities& SingleThreadProxy::GetRendererCapabilities() const {
   DCHECK(Proxy::IsMainThread());
   DCHECK(!layer_tree_host_->output_surface_lost());
   return renderer_capabilities_for_main_thread_;
 }

 void SingleThreadProxy::SetNeedsAnimate() {
   TRACE_EVENT0("cc", "SingleThreadProxy::SetNeedsAnimate");
   DCHECK(Proxy::IsMainThread());
   client_->ScheduleAnimation();
   SetNeedsCommit();
 }

 void SingleThreadProxy::SetNeedsUpdateLayers() {
   TRACE_EVENT0("cc", "SingleThreadProxy::SetNeedsUpdateLayers");
   DCHECK(Proxy::IsMainThread());
   SetNeedsCommit();
 }

 void SingleThreadProxy::DoCommit(const BeginFrameArgs& begin_frame_args) {
   TRACE_EVENT0("cc", "SingleThreadProxy::DoCommit");
   DCHECK(Proxy::IsMainThread());
   layer_tree_host_->WillBeginMainFrame();
   layer_tree_host_->BeginMainFrame(begin_frame_args);
   layer_tree_host_->AnimateLayers(begin_frame_args.frame_time);
   layer_tree_host_->Layout();
   commit_requested_ = false;

   if (PrioritizedResourceManager* contents_texture_manager =
           layer_tree_host_->contents_texture_manager()) {
     contents_texture_manager->UnlinkAndClearEvictedBackings();
     contents_texture_manager->SetMaxMemoryLimitBytes(
         layer_tree_host_impl_->memory_allocation_limit_bytes());
     contents_texture_manager->SetExternalPriorityCutoff(
         layer_tree_host_impl_->memory_allocation_priority_cutoff());
   }

   scoped_ptr<ResourceUpdateQueue> queue =
       make_scoped_ptr(new ResourceUpdateQueue);

   layer_tree_host_->UpdateLayers(queue.get());

   layer_tree_host_->WillCommit();

   // Commit immediately.
   {
     DebugScopedSetMainThreadBlocked main_thread_blocked(this);
     DebugScopedSetImplThread impl(this);

     // This CapturePostTasks should be destroyed before CommitComplete() is
     // called since that goes out to the embedder, and we want the embedder
     // to receive its callbacks before that.
     BlockingTaskRunner::CapturePostTasks blocked;

     layer_tree_host_impl_->BeginCommit();

     if (PrioritizedResourceManager* contents_texture_manager =
         layer_tree_host_->contents_texture_manager()) {
       contents_texture_manager->PushTexturePrioritiesToBackings();
     }
     layer_tree_host_->BeginCommitOnImplThread(layer_tree_host_impl_.get());

     scoped_ptr<ResourceUpdateController> update_controller =
         ResourceUpdateController::Create(
             NULL,
             MainThreadTaskRunner(),
             queue.Pass(),
             layer_tree_host_impl_->resource_provider());
     update_controller->Finalize();

     if (layer_tree_host_impl_->EvictedUIResourcesExist())
       layer_tree_host_->RecreateUIResources();

     layer_tree_host_->FinishCommitOnImplThread(layer_tree_host_impl_.get());

     layer_tree_host_impl_->CommitComplete();

     UpdateBackgroundAnimateTicking();

 #if DCHECK_IS_ON
     // In the single-threaded case, the scale and scroll deltas should never be
     // touched on the impl layer tree.
     scoped_ptr<ScrollAndScaleSet> scroll_info =
         layer_tree_host_impl_->ProcessScrollDeltas();
     DCHECK(!scroll_info->scrolls.size());
     DCHECK_EQ(1.f, scroll_info->page_scale_delta);
 #endif

     RenderingStatsInstrumentation* stats_instrumentation =
         layer_tree_host_->rendering_stats_instrumentation();
     benchmark_instrumentation::IssueMainThreadRenderingStatsEvent(
         stats_instrumentation->main_thread_rendering_stats());
     stats_instrumentation->AccumulateAndClearMainThreadStats();
   }
   layer_tree_host_->CommitComplete();
   layer_tree_host_->DidBeginMainFrame();
   timing_history_.DidCommit();

   next_frame_is_newly_committed_frame_ = true;
 }

 void SingleThreadProxy::SetNeedsCommit() {
   DCHECK(Proxy::IsMainThread());
   DebugScopedSetImplThread impl(this);
   client_->ScheduleComposite();
   if (scheduler_on_impl_thread_)
     scheduler_on_impl_thread_->SetNeedsCommit();
   commit_requested_ = true;
 }

 void SingleThreadProxy::SetNeedsRedraw(const gfx::Rect& damage_rect) {
   TRACE_EVENT0("cc", "SingleThreadProxy::SetNeedsRedraw");
   DCHECK(Proxy::IsMainThread());
   DebugScopedSetImplThread impl(this);
   client_->ScheduleComposite();
   SetNeedsRedrawRectOnImplThread(damage_rect);
 }

 void SingleThreadProxy::SetNextCommitWaitsForActivation() {
   // There is no activation here other than commit. So do nothing.
   DCHECK(Proxy::IsMainThread());
 }

 void SingleThreadProxy::SetDeferCommits(bool defer_commits) {
   DCHECK(Proxy::IsMainThread());
   // Deferring commits only makes sense if there's a scheduler.
   if (!scheduler_on_impl_thread_)
     return;
   if (defer_commits_ == defer_commits)
     return;

   if (defer_commits)
     TRACE_EVENT_ASYNC_BEGIN0("cc", "SingleThreadProxy::SetDeferCommits", this);
   else
     TRACE_EVENT_ASYNC_END0("cc", "SingleThreadProxy::SetDeferCommits", this);

   defer_commits_ = defer_commits;
   if (!defer_commits_ && commit_was_deferred_) {
     commit_was_deferred_ = false;
     BeginMainFrame();
   }
 }

 bool SingleThreadProxy::CommitRequested() const {
   DCHECK(Proxy::IsMainThread());
   return commit_requested_;
 }

 bool SingleThreadProxy::BeginMainFrameRequested() const {
   DCHECK(Proxy::IsMainThread());
   // If there is no scheduler, then there can be no pending begin frame,
   // as all frames are all manually initiated by the embedder of cc.
   if (!scheduler_on_impl_thread_)
     return false;
   return commit_requested_;
 }

 size_t SingleThreadProxy::MaxPartialTextureUpdates() const {
   return std::numeric_limits<size_t>::max();
 }

 void SingleThreadProxy::Stop() {
   TRACE_EVENT0("cc", "SingleThreadProxy::stop");
   DCHECK(Proxy::IsMainThread());
   {
     DebugScopedSetMainThreadBlocked main_thread_blocked(this);
     DebugScopedSetImplThread impl(this);

     BlockingTaskRunner::CapturePostTasks blocked;
     layer_tree_host_->DeleteContentsTexturesOnImplThread(
         layer_tree_host_impl_->resource_provider());
     scheduler_on_impl_thread_.reset();
     layer_tree_host_impl_.reset();
   }
   layer_tree_host_ = NULL;
 }

 void SingleThreadProxy::OnCanDrawStateChanged(bool can_draw) {
   TRACE_EVENT1(
       "cc", "SingleThreadProxy::OnCanDrawStateChanged", "can_draw", can_draw);
   DCHECK(Proxy::IsImplThread());
   UpdateBackgroundAnimateTicking();
   if (scheduler_on_impl_thread_)
     scheduler_on_impl_thread_->SetCanDraw(can_draw);
 }

 void SingleThreadProxy::NotifyReadyToActivate() {
   // Impl-side painting only.
   NOTREACHED();
 }

 void SingleThreadProxy::SetNeedsRedrawOnImplThread() {
   client_->ScheduleComposite();
   if (scheduler_on_impl_thread_)
     scheduler_on_impl_thread_->SetNeedsRedraw();
 }

 void SingleThreadProxy::SetNeedsAnimateOnImplThread() {
   SetNeedsRedrawOnImplThread();
 }

 void SingleThreadProxy::SetNeedsManageTilesOnImplThread() {
   // Impl-side painting only.
   NOTREACHED();
 }

 void SingleThreadProxy::SetNeedsRedrawRectOnImplThread(
     const gfx::Rect& damage_rect) {
   layer_tree_host_impl_->SetViewportDamage(damage_rect);
   SetNeedsRedrawOnImplThread();
 }

 void SingleThreadProxy::DidInitializeVisibleTileOnImplThread() {
   // Impl-side painting only.
   NOTREACHED();
 }

 void SingleThreadProxy::SetNeedsCommitOnImplThread() {
   client_->ScheduleComposite();
   if (scheduler_on_impl_thread_)
     scheduler_on_impl_thread_->SetNeedsCommit();
 }

 void SingleThreadProxy::PostAnimationEventsToMainThreadOnImplThread(
     scoped_ptr<AnimationEventsVector> events) {
   TRACE_EVENT0(
       "cc", "SingleThreadProxy::PostAnimationEventsToMainThreadOnImplThread");
   DCHECK(Proxy::IsImplThread());
   DebugScopedSetMainThread main(this);
   layer_tree_host_->SetAnimationEvents(events.Pass());
 }

 bool SingleThreadProxy::ReduceContentsTextureMemoryOnImplThread(
     size_t limit_bytes,
     int priority_cutoff) {
   DCHECK(IsImplThread());
   PrioritizedResourceManager* contents_texture_manager =
       layer_tree_host_->contents_texture_manager();

   ResourceProvider* resource_provider =
       layer_tree_host_impl_->resource_provider();

   if (!contents_texture_manager || !resource_provider)
     return false;

   return contents_texture_manager->ReduceMemoryOnImplThread(
       limit_bytes, priority_cutoff, resource_provider);
 }

 bool SingleThreadProxy::IsInsideDraw() { return inside_draw_; }

 void SingleThreadProxy::UpdateRendererCapabilitiesOnImplThread() {
   DCHECK(IsImplThread());
   renderer_capabilities_for_main_thread_ =
       layer_tree_host_impl_->GetRendererCapabilities().MainThreadCapabilities();
 }

 void SingleThreadProxy::DidManageTiles() {
   // Impl-side painting only.
   NOTREACHED();
 }

 void SingleThreadProxy::DidLoseOutputSurfaceOnImplThread() {
   TRACE_EVENT0("cc", "SingleThreadProxy::DidLoseOutputSurfaceOnImplThread");
   {
     DebugScopedSetMainThread main(this);
     // This must happen before we notify the scheduler as it may try to recreate
     // the output surface if already in BEGIN_IMPL_FRAME_STATE_IDLE.
     layer_tree_host_->DidLoseOutputSurface();
   }
   client_->DidAbortSwapBuffers();
   if (scheduler_on_impl_thread_)
     scheduler_on_impl_thread_->DidLoseOutputSurface();
 }

 void SingleThreadProxy::DidSwapBuffersOnImplThread() {
   TRACE_EVENT0("cc", "SingleThreadProxy::DidSwapBuffersOnImplThread");
   if (scheduler_on_impl_thread_)
     scheduler_on_impl_thread_->DidSwapBuffers();
   client_->DidPostSwapBuffers();
 }

 void SingleThreadProxy::DidSwapBuffersCompleteOnImplThread() {
   TRACE_EVENT0("cc", "SingleThreadProxy::DidSwapBuffersCompleteOnImplThread");
   if (scheduler_on_impl_thread_)
     scheduler_on_impl_thread_->DidSwapBuffersComplete();
   layer_tree_host_->DidCompleteSwapBuffers();
 }

 void SingleThreadProxy::BeginFrame(const BeginFrameArgs& args) {
   TRACE_EVENT0("cc", "SingleThreadProxy::BeginFrame");
   if (scheduler_on_impl_thread_)
     scheduler_on_impl_thread_->BeginImplFrame(args);
 }

 void SingleThreadProxy::CompositeImmediately(base::TimeTicks frame_begin_time) {
   TRACE_EVENT0("cc", "SingleThreadProxy::CompositeImmediately");
   DCHECK(Proxy::IsMainThread());
   DCHECK(!layer_tree_host_->output_surface_lost());

   BeginFrameArgs begin_frame_args = BeginFrameArgs::Create(
       frame_begin_time, base::TimeTicks(), BeginFrameArgs::DefaultInterval());
   DoCommit(begin_frame_args);

   LayerTreeHostImpl::FrameData frame;
   DoComposite(frame_begin_time, &frame);
 }

 void SingleThreadProxy::AsValueInto(base::debug::TracedValue* state) const {
   // The following line casts away const modifiers because it is just
   // setting debug state. We still want the AsValue() function and its
   // call chain to be const throughout.
   DebugScopedSetImplThread impl(const_cast<SingleThreadProxy*>(this));

   state->BeginDictionary("layer_tree_host_impl");
   layer_tree_host_impl_->AsValueInto(state);
   state->EndDictionary();
 }

 void SingleThreadProxy::ForceSerializeOnSwapBuffers() {
   {
     DebugScopedSetImplThread impl(this);
     if (layer_tree_host_impl_->renderer()) {
       DCHECK(!layer_tree_host_->output_surface_lost());
       layer_tree_host_impl_->renderer()->DoNoOp();
     }
   }
 }

 bool SingleThreadProxy::SupportsImplScrolling() const {
   return false;
 }

 bool SingleThreadProxy::ShouldComposite() const {
   DCHECK(Proxy::IsImplThread());
   return layer_tree_host_impl_->visible() &&
          layer_tree_host_impl_->CanDraw();
 }

 void SingleThreadProxy::UpdateBackgroundAnimateTicking() {
   DCHECK(Proxy::IsImplThread());
   layer_tree_host_impl_->UpdateBackgroundAnimateTicking(
       !ShouldComposite() && layer_tree_host_impl_->active_tree()->root_layer());
 }

 DrawResult SingleThreadProxy::DoComposite(base::TimeTicks frame_begin_time,
                                           LayerTreeHostImpl::FrameData* frame) {
   TRACE_EVENT0("cc", "SingleThreadProxy::DoComposite");
   DCHECK(!layer_tree_host_->output_surface_lost());

   {
     DebugScopedSetImplThread impl(this);
     base::AutoReset<bool> mark_inside(&inside_draw_, true);

     // We guard PrepareToDraw() with CanDraw() because it always returns a valid
     // frame, so can only be used when such a frame is possible. Since
     // DrawLayers() depends on the result of PrepareToDraw(), it is guarded on
     // CanDraw() as well.
     if (!ShouldComposite()) {
       UpdateBackgroundAnimateTicking();
       return DRAW_ABORTED_CANT_DRAW;
     }

     timing_history_.DidStartDrawing();

     layer_tree_host_impl_->Animate(
         layer_tree_host_impl_->CurrentBeginFrameArgs().frame_time);
     UpdateBackgroundAnimateTicking();

     if (!layer_tree_host_impl_->IsContextLost()) {
       layer_tree_host_impl_->PrepareToDraw(frame);
       layer_tree_host_impl_->DrawLayers(frame, frame_begin_time);
       layer_tree_host_impl_->DidDrawAllLayers(*frame);
     }

     bool start_ready_animations = true;
     layer_tree_host_impl_->UpdateAnimationState(start_ready_animations);

     layer_tree_host_impl_->ResetCurrentBeginFrameArgsForNextFrame();

     timing_history_.DidFinishDrawing();
   }

   {
     DebugScopedSetImplThread impl(this);

     if (layer_tree_host_impl_->IsContextLost()) {
       DidLoseOutputSurfaceOnImplThread();
     } else {
       // This CapturePostTasks should be destroyed before
       // DidCommitAndDrawFrame() is called since that goes out to the
       // embedder,
       // and we want the embedder to receive its callbacks before that.
       // NOTE: This maintains consistent ordering with the ThreadProxy since
       // the DidCommitAndDrawFrame() must be post-tasked from the impl thread
       // there as the main thread is not blocked, so any posted tasks inside
       // the swap buffers will execute first.
       DebugScopedSetMainThreadBlocked main_thread_blocked(this);

       BlockingTaskRunner::CapturePostTasks blocked;
       layer_tree_host_impl_->SwapBuffers(*frame);
     }
   }
   DidCommitAndDrawFrame();

   return DRAW_SUCCESS;
 }

 void SingleThreadProxy::DidCommitAndDrawFrame() {
   if (next_frame_is_newly_committed_frame_) {
     DebugScopedSetMainThread main(this);
     next_frame_is_newly_committed_frame_ = false;
     layer_tree_host_->DidCommitAndDrawFrame();
   }
 }

 bool SingleThreadProxy::MainFrameWillHappenForTesting() {
   return false;
 }

 void SingleThreadProxy::SetNeedsBeginFrame(bool enable) {
   layer_tree_host_impl_->SetNeedsBeginFrame(enable);
 }

 void SingleThreadProxy::WillBeginImplFrame(const BeginFrameArgs& args) {
   layer_tree_host_impl_->WillBeginImplFrame(args);
 }

 void SingleThreadProxy::ScheduledActionSendBeginMainFrame() {
   TRACE_EVENT0("cc", "SingleThreadProxy::ScheduledActionSendBeginMainFrame");
   // Although this proxy is single-threaded, it's problematic to synchronously
   // have BeginMainFrame happen after ScheduledActionSendBeginMainFrame.  This
   // could cause a commit to occur in between a series of SetNeedsCommit calls
   // (i.e. property modifications) causing some to fall on one frame and some to
   // fall on the next.  Doing it asynchronously instead matches the semantics of
   // ThreadProxy::SetNeedsCommit where SetNeedsCommit will not cause a
   // synchronous commit.
   MainThreadTaskRunner()->PostTask(
       FROM_HERE,
       base::Bind(&SingleThreadProxy::BeginMainFrame,
                  weak_factory_.GetWeakPtr()));
 }

 void SingleThreadProxy::BeginMainFrame() {
   if (defer_commits_) {
     DCHECK(!commit_was_deferred_);
     commit_was_deferred_ = true;
     layer_tree_host_->DidDeferCommit();
     return;
   }

   // This checker assumes NotifyReadyToCommit below causes a synchronous commit.
   ScopedAbortRemainingSwapPromises swap_promise_checker(layer_tree_host_);

   if (!layer_tree_host_->visible()) {
     TRACE_EVENT_INSTANT0("cc", "EarlyOut_NotVisible", TRACE_EVENT_SCOPE_THREAD);
     BeginMainFrameAbortedOnImplThread();
     return;
   }

   if (layer_tree_host_->output_surface_lost()) {
     TRACE_EVENT_INSTANT0(
         "cc", "EarlyOut_OutputSurfaceLost", TRACE_EVENT_SCOPE_THREAD);
     BeginMainFrameAbortedOnImplThread();
     return;
   }

   timing_history_.DidBeginMainFrame();

   DCHECK(scheduler_on_impl_thread_);
   scheduler_on_impl_thread_->NotifyBeginMainFrameStarted();
   scheduler_on_impl_thread_->NotifyReadyToCommit();
 }

 void SingleThreadProxy::BeginMainFrameAbortedOnImplThread() {
   DebugScopedSetImplThread impl(this);
   DCHECK(scheduler_on_impl_thread_->CommitPending());
   DCHECK(!layer_tree_host_impl_->pending_tree());

   // TODO(enne): SingleThreadProxy does not support cancelling commits yet so
   // did_handle is always false.
   bool did_handle = false;
   layer_tree_host_impl_->BeginMainFrameAborted(did_handle);
   scheduler_on_impl_thread_->BeginMainFrameAborted(did_handle);
 }

 DrawResult SingleThreadProxy::ScheduledActionDrawAndSwapIfPossible() {
   DebugScopedSetImplThread impl(this);
   if (layer_tree_host_impl_->IsContextLost()) {
     DidCommitAndDrawFrame();
     return DRAW_SUCCESS;
   }

   LayerTreeHostImpl::FrameData frame;
   return DoComposite(layer_tree_host_impl_->CurrentBeginFrameArgs().frame_time,
                      &frame);
 }

 DrawResult SingleThreadProxy::ScheduledActionDrawAndSwapForced() {
   NOTREACHED();
   return INVALID_RESULT;
 }

 void SingleThreadProxy::ScheduledActionCommit() {
   DebugScopedSetMainThread main(this);
   DoCommit(layer_tree_host_impl_->CurrentBeginFrameArgs());
 }

 void SingleThreadProxy::ScheduledActionAnimate() {
   TRACE_EVENT0("cc", "ScheduledActionAnimate");
   layer_tree_host_impl_->Animate(
       layer_tree_host_impl_->CurrentBeginFrameArgs().frame_time);
 }

 void SingleThreadProxy::ScheduledActionUpdateVisibleTiles() {
   // Impl-side painting only.
   NOTREACHED();
 }

 void SingleThreadProxy::ScheduledActionActivateSyncTree() {
 }

 void SingleThreadProxy::ScheduledActionBeginOutputSurfaceCreation() {
   DebugScopedSetMainThread main(this);
   DCHECK(scheduler_on_impl_thread_);
   // If possible, create the output surface in a post task.  Synchronously
   // creating the output surface makes tests more awkward since this differs
   // from the ThreadProxy behavior.  However, sometimes there is no
   // task runner.
   if (Proxy::MainThreadTaskRunner()) {
     MainThreadTaskRunner()->PostTask(
         FROM_HERE,
         base::Bind(&SingleThreadProxy::CreateAndInitializeOutputSurface,
                    weak_factory_.GetWeakPtr()));
   } else {
     CreateAndInitializeOutputSurface();
   }
 }

 void SingleThreadProxy::ScheduledActionManageTiles() {
   // Impl-side painting only.
   NOTREACHED();
 }

 void SingleThreadProxy::DidAnticipatedDrawTimeChange(base::TimeTicks time) {
 }

 base::TimeDelta SingleThreadProxy::DrawDurationEstimate() {
   return timing_history_.DrawDurationEstimate();
 }

 base::TimeDelta SingleThreadProxy::BeginMainFrameToCommitDurationEstimate() {
   return timing_history_.BeginMainFrameToCommitDurationEstimate();
 }

 base::TimeDelta SingleThreadProxy::CommitToActivateDurationEstimate() {
   return timing_history_.CommitToActivateDurationEstimate();
 }

 void SingleThreadProxy::DidBeginImplFrameDeadline() {
   layer_tree_host_impl_->ResetCurrentBeginFrameArgsForNextFrame();
 }

 }  // namespace cc