cc/trees/thread

/* [<][>][^][v][top][bottom][index][help] */
This source file includes following definitions.
Create
compositor_thread_vars_unsafe_
weak_factory
main_thread_inside_commit
contents_texture_manager
weak_factory
CompositeAndReadback
ForceCommitForReadbackOnImplThread
FinishAllRendering
IsStarted
SetLayerTreeHostClientReady
SetLayerTreeHostClientReadyOnImplThread
SetVisible
SetVisibleOnImplThread
UpdateBackgroundAnimateTicking
DoCreateAndInitializeOutputSurface
SetRendererCapabilitiesMainThreadCopy
OnOutputSurfaceInitializeAttempted
SendCommitRequestToImplThreadIfNeeded
GetRendererCapabilities
SetNeedsAnimate
SetNeedsUpdateLayers
SetNeedsCommit
UpdateRendererCapabilitiesOnImplThread
DidLoseOutputSurfaceOnImplThread
CheckOutputSurfaceStatusOnImplThread
OnSwapBuffersCompleteOnImplThread
SetNeedsBeginImplFrame
BeginImplFrame
OnCanDrawStateChanged
NotifyReadyToActivate
SetNeedsCommitOnImplThread
PostAnimationEventsToMainThreadOnImplThread
ReduceContentsTextureMemoryOnImplThread
SendManagedMemoryStats
IsInsideDraw
SetNeedsRedraw
SetNextCommitWaitsForActivation
SetDeferCommits
CommitRequested
BeginMainFrameRequested
SetNeedsRedrawOnImplThread
SetNeedsManageTilesOnImplThread
SetNeedsRedrawRectOnImplThread
SetSwapUsedIncompleteTileOnImplThread
DidInitializeVisibleTileOnImplThread
MainThreadHasStoppedFlinging
MainThreadHasStoppedFlingingOnImplThread
NotifyInputThrottledUntilCommit
SetInputThrottledUntilCommitOnImplThread
layer_tree_host
layer_tree_host
main
main
blocked_main
blocked_main
impl
impl
Start
Stop
ForceSerializeOnSwapBuffers
ForceSerializeOnSwapBuffersOnImplThread
SetDebugState
SetDebugStateOnImplThread
FinishAllRenderingOnImplThread
ScheduledActionSendBeginMainFrame
BeginMainFrame
StartCommitOnImplThread
BeginMainFrameAbortedOnImplThread
ScheduledActionCommit
ScheduledActionUpdateVisibleTiles
ScheduledActionActivatePendingTree
ScheduledActionBeginOutputSurfaceCreation
DrawSwapReadbackInternal
AcquireLayerTextures
AcquireLayerTexturesForMainThreadOnImplThread
ScheduledActionAcquireLayerTexturesForMainThread
ScheduledActionManageTiles
ScheduledActionDrawAndSwapIfPossible
ScheduledActionDrawAndSwapForced
ScheduledActionDrawAndReadback
DidAnticipatedDrawTimeChange
DrawDurationEstimate
BeginMainFrameToCommitDurationEstimate
CommitToActivateDurationEstimate
DidBeginImplFrameDeadline
ReadyToFinalizeTextureUpdates
DidCommitAndDrawFrame
DidCompleteSwapBuffers
SetAnimationEvents
CreateAndInitializeOutputSurface
HasInitializedOutputSurfaceOnImplThread
InitializeImplOnImplThread
InitializeOutputSurfaceOnImplThread
FinishGLOnImplThread
LayerTreeHostClosedOnImplThread
MaxPartialTextureUpdates
evicted_ui_resources
AsValue
AsValueOnImplThread
CommitPendingForTesting
CommitPendingOnImplThreadForTesting
SchedulerStateAsValueForTesting
SchedulerStateAsValueOnImplThreadForTesting
RenewTreePriority
RenewTreePriorityOnImplThread
RequestScrollbarAnimationOnImplThread
StartScrollbarAnimationOnImplThread
DidActivatePendingTree
DidManageTiles
// 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/thread_proxy.h"

#include <algorithm>
#include <string>

#include "base/auto_reset.h"
#include "base/bind.h"
#include "base/debug/trace_event.h"
#include "base/debug/trace_event_synthetic_delay.h"
#include "base/metrics/histogram.h"
#include "cc/base/swap_promise.h"
#include "cc/debug/benchmark_instrumentation.h"
#include "cc/debug/devtools_instrumentation.h"
#include "cc/input/input_handler.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/scheduler/delay_based_time_source.h"
#include "cc/scheduler/frame_rate_controller.h"
#include "cc/scheduler/scheduler.h"
#include "cc/trees/blocking_task_runner.h"
#include "cc/trees/layer_tree_host.h"
#include "cc/trees/layer_tree_impl.h"
#include "ui/gfx/frame_time.h"

namespace {

// Measured in seconds.
const double kSmoothnessTakesPriorityExpirationDelay = 0.25;

class SwapPromiseChecker {
 public:
  explicit SwapPromiseChecker(cc::LayerTreeHost* layer_tree_host)
      : layer_tree_host_(layer_tree_host) {}

  ~SwapPromiseChecker() {
    layer_tree_host_->BreakSwapPromises(cc::SwapPromise::COMMIT_FAILS);
  }

 private:
  cc::LayerTreeHost* layer_tree_host_;
};

}  // namespace

namespace cc {

struct ThreadProxy::ReadbackRequest {
  CompletionEvent completion;
  bool success;
  void* pixels;
  gfx::Rect rect;
};

struct ThreadProxy::CommitPendingRequest {
  CompletionEvent completion;
  bool commit_pending;
};

struct ThreadProxy::SchedulerStateRequest {
  CompletionEvent completion;
  scoped_ptr<base::Value> state;
};

scoped_ptr<Proxy> ThreadProxy::Create(
    LayerTreeHost* layer_tree_host,
    scoped_refptr<base::SingleThreadTaskRunner> impl_task_runner) {
  return make_scoped_ptr(new ThreadProxy(layer_tree_host, impl_task_runner))
      .PassAs<Proxy>();
}

ThreadProxy::ThreadProxy(
    LayerTreeHost* layer_tree_host,
    scoped_refptr<base::SingleThreadTaskRunner> impl_task_runner)
    : Proxy(impl_task_runner),
      main_thread_only_vars_unsafe_(this, layer_tree_host->id()),
      main_thread_or_blocked_vars_unsafe_(layer_tree_host),
      compositor_thread_vars_unsafe_(this, layer_tree_host->id()) {
  TRACE_EVENT0("cc", "ThreadProxy::ThreadProxy");
  DCHECK(IsMainThread());
  DCHECK(this->layer_tree_host());
}

ThreadProxy::MainThreadOnly::MainThreadOnly(ThreadProxy* proxy,
                                            int layer_tree_host_id)
    : layer_tree_host_id(layer_tree_host_id),
      animate_requested(false),
      commit_requested(false),
      commit_request_sent_to_impl_thread(false),
      created_offscreen_context_provider(false),
      started(false),
      textures_acquired(true),
      in_composite_and_readback(false),
      manage_tiles_pending(false),
      can_cancel_commit(true),
      defer_commits(false),
      weak_factory(proxy) {}

ThreadProxy::MainThreadOnly::~MainThreadOnly() {}

ThreadProxy::MainThreadOrBlockedMainThread::MainThreadOrBlockedMainThread(
    LayerTreeHost* host)
    : layer_tree_host(host),
      commit_waits_for_activation(false),
      main_thread_inside_commit(false) {}

ThreadProxy::MainThreadOrBlockedMainThread::~MainThreadOrBlockedMainThread() {}

PrioritizedResourceManager*
ThreadProxy::MainThreadOrBlockedMainThread::contents_texture_manager() {
  return layer_tree_host->contents_texture_manager();
}

ThreadProxy::CompositorThreadOnly::CompositorThreadOnly(ThreadProxy* proxy,
                                                        int layer_tree_host_id)
    : layer_tree_host_id(layer_tree_host_id),
      contents_texture_manager(NULL),
      begin_main_frame_sent_completion_event(NULL),
      readback_request(NULL),
      commit_completion_event(NULL),
      completion_event_for_commit_held_on_tree_activation(NULL),
      texture_acquisition_completion_event(NULL),
      next_frame_is_newly_committed_frame(false),
      inside_draw(false),
      input_throttled_until_commit(false),
      animations_frozen_until_next_draw(false),
      renew_tree_priority_pending(false),
      weak_factory(proxy) {}

ThreadProxy::CompositorThreadOnly::~CompositorThreadOnly() {}

ThreadProxy::~ThreadProxy() {
  TRACE_EVENT0("cc", "ThreadProxy::~ThreadProxy");
  DCHECK(IsMainThread());
  DCHECK(!main().started);
}

bool ThreadProxy::CompositeAndReadback(void* pixels, const gfx::Rect& rect) {
  TRACE_EVENT0("cc", "ThreadProxy::CompositeAndReadback");
  DCHECK(IsMainThread());
  DCHECK(layer_tree_host());

  if (main().defer_commits) {
    TRACE_EVENT0("cc", "CompositeAndReadback_DeferCommit");
    return false;
  }

  if (!layer_tree_host()->InitializeOutputSurfaceIfNeeded()) {
    TRACE_EVENT_INSTANT0("cc",
                         "CompositeAndReadback_EarlyOut_LR_Uninitialized",
                         TRACE_EVENT_SCOPE_THREAD);
    return false;
  }

  // Perform a synchronous commit with an associated readback.
  ReadbackRequest request;
  request.rect = rect;
  request.pixels = pixels;
  {
    DebugScopedSetMainThreadBlocked main_thread_blocked(this);
    CompletionEvent begin_main_frame_sent_completion;
    Proxy::ImplThreadTaskRunner()->PostTask(
        FROM_HERE,
        base::Bind(&ThreadProxy::ForceCommitForReadbackOnImplThread,
                   impl_thread_weak_ptr_,
                   &begin_main_frame_sent_completion,
                   &request));
    begin_main_frame_sent_completion.Wait();
  }

  main().in_composite_and_readback = true;
  // This is the forced commit.
  // Note: The Impl thread also queues a separate BeginMainFrame on the
  // main thread, which will be called after this CompositeAndReadback
  // completes, to replace the forced commit.
  BeginMainFrame(scoped_ptr<BeginMainFrameAndCommitState>());
  main().in_composite_and_readback = false;

  // Composite and readback requires a second commit to undo any changes
  // that it made.
  main().can_cancel_commit = false;

  request.completion.Wait();
  return request.success;
}

void ThreadProxy::ForceCommitForReadbackOnImplThread(
    CompletionEvent* begin_main_frame_sent_completion,
    ReadbackRequest* request) {
  TRACE_EVENT0("cc", "ThreadProxy::ForceCommitForReadbackOnImplThread");
  DCHECK(IsImplThread());
  DCHECK(!impl().begin_main_frame_sent_completion_event);
  DCHECK(!impl().readback_request);

  if (!impl().layer_tree_host_impl) {
    begin_main_frame_sent_completion->Signal();
    request->success = false;
    request->completion.Signal();
    return;
  }

  impl().readback_request = request;

  impl().scheduler->SetNeedsForcedCommitForReadback();
  if (impl().scheduler->IsBeginMainFrameSent()) {
    begin_main_frame_sent_completion->Signal();
    return;
  }

  impl().begin_main_frame_sent_completion_event =
      begin_main_frame_sent_completion;
}

void ThreadProxy::FinishAllRendering() {
  DCHECK(Proxy::IsMainThread());
  DCHECK(!main().defer_commits);

  // Make sure all GL drawing is finished on the impl thread.
  DebugScopedSetMainThreadBlocked main_thread_blocked(this);
  CompletionEvent completion;
  Proxy::ImplThreadTaskRunner()->PostTask(
      FROM_HERE,
      base::Bind(&ThreadProxy::FinishAllRenderingOnImplThread,
                 impl_thread_weak_ptr_,
                 &completion));
  completion.Wait();
}

bool ThreadProxy::IsStarted() const {
  DCHECK(Proxy::IsMainThread());
  return main().started;
}

void ThreadProxy::SetLayerTreeHostClientReady() {
  TRACE_EVENT0("cc", "ThreadProxy::SetLayerTreeHostClientReady");
  Proxy::ImplThreadTaskRunner()->PostTask(
      FROM_HERE,
      base::Bind(&ThreadProxy::SetLayerTreeHostClientReadyOnImplThread,
                 impl_thread_weak_ptr_));
}

void ThreadProxy::SetLayerTreeHostClientReadyOnImplThread() {
  TRACE_EVENT0("cc", "ThreadProxy::SetLayerTreeHostClientReadyOnImplThread");
  impl().scheduler->SetCanStart();
}

void ThreadProxy::SetVisible(bool visible) {
  TRACE_EVENT0("cc", "ThreadProxy::SetVisible");
  DebugScopedSetMainThreadBlocked main_thread_blocked(this);

  CompletionEvent completion;
  Proxy::ImplThreadTaskRunner()->PostTask(
      FROM_HERE,
      base::Bind(&ThreadProxy::SetVisibleOnImplThread,
                 impl_thread_weak_ptr_,
                 &completion,
                 visible));
  completion.Wait();
}

void ThreadProxy::SetVisibleOnImplThread(CompletionEvent* completion,
                                         bool visible) {
  TRACE_EVENT0("cc", "ThreadProxy::SetVisibleOnImplThread");
  impl().layer_tree_host_impl->SetVisible(visible);
  impl().scheduler->SetVisible(visible);
  UpdateBackgroundAnimateTicking();
  completion->Signal();
}

void ThreadProxy::UpdateBackgroundAnimateTicking() {
  bool should_background_tick =
      !impl().scheduler->WillDrawIfNeeded() &&
      impl().layer_tree_host_impl->active_tree()->root_layer();
  impl().layer_tree_host_impl->UpdateBackgroundAnimateTicking(
      should_background_tick);
  if (should_background_tick)
    impl().animations_frozen_until_next_draw = false;
}

void ThreadProxy::DoCreateAndInitializeOutputSurface() {
  TRACE_EVENT0("cc", "ThreadProxy::DoCreateAndInitializeOutputSurface");
  DCHECK(IsMainThread());

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

  RendererCapabilities capabilities;
  bool success = !!output_surface;
  if (!success) {
    OnOutputSurfaceInitializeAttempted(false, capabilities);
    return;
  }

  scoped_refptr<ContextProvider> offscreen_context_provider;
  if (main().created_offscreen_context_provider) {
    offscreen_context_provider =
        layer_tree_host()->client()->OffscreenContextProvider();
    success = !!offscreen_context_provider.get();
    if (!success) {
      OnOutputSurfaceInitializeAttempted(false, capabilities);
      return;
    }
  }

  success = false;
  {
    // Make a blocking call to InitializeOutputSurfaceOnImplThread. The results
    // of that call are pushed into the success and capabilities local
    // variables.
    CompletionEvent completion;
    DebugScopedSetMainThreadBlocked main_thread_blocked(this);

    Proxy::ImplThreadTaskRunner()->PostTask(
        FROM_HERE,
        base::Bind(&ThreadProxy::InitializeOutputSurfaceOnImplThread,
                   impl_thread_weak_ptr_,
                   &completion,
                   base::Passed(&output_surface),
                   offscreen_context_provider,
                   &success,
                   &capabilities));
    completion.Wait();
  }

  OnOutputSurfaceInitializeAttempted(success, capabilities);
}

void ThreadProxy::SetRendererCapabilitiesMainThreadCopy(
    const RendererCapabilities& capabilities) {
  main().renderer_capabilities_main_thread_copy = capabilities;
}

void ThreadProxy::OnOutputSurfaceInitializeAttempted(
    bool success,
    const RendererCapabilities& capabilities) {
  DCHECK(IsMainThread());
  DCHECK(layer_tree_host());

  if (success) {
    main().renderer_capabilities_main_thread_copy = capabilities;
  }

  LayerTreeHost::CreateResult result =
      layer_tree_host()->OnCreateAndInitializeOutputSurfaceAttempted(success);
  if (result == LayerTreeHost::CreateFailedButTryAgain) {
    if (!main().output_surface_creation_callback.callback().is_null()) {
      Proxy::MainThreadTaskRunner()->PostTask(
          FROM_HERE, main().output_surface_creation_callback.callback());
    }
  } else {
    main().output_surface_creation_callback.Cancel();
  }
}

void ThreadProxy::SendCommitRequestToImplThreadIfNeeded() {
  DCHECK(IsMainThread());
  if (main().commit_request_sent_to_impl_thread)
    return;
  main().commit_request_sent_to_impl_thread = true;
  Proxy::ImplThreadTaskRunner()->PostTask(
      FROM_HERE,
      base::Bind(&ThreadProxy::SetNeedsCommitOnImplThread,
                 impl_thread_weak_ptr_));
}

const RendererCapabilities& ThreadProxy::GetRendererCapabilities() const {
  DCHECK(IsMainThread());
  DCHECK(!layer_tree_host()->output_surface_lost());
  return main().renderer_capabilities_main_thread_copy;
}

void ThreadProxy::SetNeedsAnimate() {
  DCHECK(IsMainThread());
  if (main().animate_requested)
    return;

  TRACE_EVENT0("cc", "ThreadProxy::SetNeedsAnimate");
  main().animate_requested = true;
  SendCommitRequestToImplThreadIfNeeded();
}

void ThreadProxy::SetNeedsUpdateLayers() {
  DCHECK(IsMainThread());

  if (main().commit_request_sent_to_impl_thread)
    return;
  TRACE_EVENT0("cc", "ThreadProxy::SetNeedsUpdateLayers");

  SendCommitRequestToImplThreadIfNeeded();
}

void ThreadProxy::SetNeedsCommit() {
  DCHECK(IsMainThread());
  // Unconditionally set here to handle SetNeedsCommit calls during a commit.
  main().can_cancel_commit = false;

  if (main().commit_requested)
    return;
  TRACE_EVENT0("cc", "ThreadProxy::SetNeedsCommit");
  main().commit_requested = true;

  SendCommitRequestToImplThreadIfNeeded();
}

void ThreadProxy::UpdateRendererCapabilitiesOnImplThread() {
  DCHECK(IsImplThread());
  Proxy::MainThreadTaskRunner()->PostTask(
      FROM_HERE,
      base::Bind(&ThreadProxy::SetRendererCapabilitiesMainThreadCopy,
                 main_thread_weak_ptr_,
                 impl()
                     .layer_tree_host_impl->GetRendererCapabilities()
                     .MainThreadCapabilities()));
}

void ThreadProxy::DidLoseOutputSurfaceOnImplThread() {
  TRACE_EVENT0("cc", "ThreadProxy::DidLoseOutputSurfaceOnImplThread");
  DCHECK(IsImplThread());
  CheckOutputSurfaceStatusOnImplThread();
}

void ThreadProxy::CheckOutputSurfaceStatusOnImplThread() {
  TRACE_EVENT0("cc", "ThreadProxy::CheckOutputSurfaceStatusOnImplThread");
  DCHECK(IsImplThread());
  if (!impl().layer_tree_host_impl->IsContextLost())
    return;
  if (ContextProvider* offscreen_contexts =
          impl().layer_tree_host_impl->offscreen_context_provider())
    offscreen_contexts->VerifyContexts();
  impl().scheduler->DidLoseOutputSurface();
}

void ThreadProxy::OnSwapBuffersCompleteOnImplThread() {
  TRACE_EVENT0("cc", "ThreadProxy::OnSwapBuffersCompleteOnImplThread");
  DCHECK(IsImplThread());
  Proxy::MainThreadTaskRunner()->PostTask(
      FROM_HERE,
      base::Bind(&ThreadProxy::DidCompleteSwapBuffers, main_thread_weak_ptr_));
}

void ThreadProxy::SetNeedsBeginImplFrame(bool enable) {
  TRACE_EVENT1("cc", "ThreadProxy::SetNeedsBeginImplFrame", "enable", enable);
  DCHECK(IsImplThread());
  impl().layer_tree_host_impl->SetNeedsBeginImplFrame(enable);
  UpdateBackgroundAnimateTicking();
}

void ThreadProxy::BeginImplFrame(const BeginFrameArgs& args) {
  TRACE_EVENT0("cc", "ThreadProxy::BeginImplFrame");
  DCHECK(IsImplThread());

  // Sample the frame time now. This time will be used for updating animations
  // when we draw.
  impl().layer_tree_host_impl->UpdateCurrentFrameTime();

  impl().scheduler->BeginImplFrame(args);
}

void ThreadProxy::OnCanDrawStateChanged(bool can_draw) {
  TRACE_EVENT1(
      "cc", "ThreadProxy::OnCanDrawStateChanged", "can_draw", can_draw);
  DCHECK(IsImplThread());
  impl().scheduler->SetCanDraw(can_draw);
  UpdateBackgroundAnimateTicking();
}

void ThreadProxy::NotifyReadyToActivate() {
  TRACE_EVENT0("cc", "ThreadProxy::NotifyReadyToActivate");
  impl().scheduler->NotifyReadyToActivate();
}

void ThreadProxy::SetNeedsCommitOnImplThread() {
  TRACE_EVENT0("cc", "ThreadProxy::SetNeedsCommitOnImplThread");
  DCHECK(IsImplThread());
  impl().scheduler->SetNeedsCommit();
}

void ThreadProxy::PostAnimationEventsToMainThreadOnImplThread(
    scoped_ptr<AnimationEventsVector> events) {
  TRACE_EVENT0("cc",
               "ThreadProxy::PostAnimationEventsToMainThreadOnImplThread");
  DCHECK(IsImplThread());
  Proxy::MainThreadTaskRunner()->PostTask(
      FROM_HERE,
      base::Bind(&ThreadProxy::SetAnimationEvents,
                 main_thread_weak_ptr_,
                 base::Passed(&events)));
}

bool ThreadProxy::ReduceContentsTextureMemoryOnImplThread(size_t limit_bytes,
                                                          int priority_cutoff) {
  DCHECK(IsImplThread());

  if (!impl().contents_texture_manager)
    return false;
  if (!impl().layer_tree_host_impl->resource_provider())
    return false;

  bool reduce_result =
      impl().contents_texture_manager->ReduceMemoryOnImplThread(
          limit_bytes,
          priority_cutoff,
          impl().layer_tree_host_impl->resource_provider());
  if (!reduce_result)
    return false;

  // The texture upload queue may reference textures that were just purged,
  // clear them from the queue.
  if (impl().current_resource_update_controller) {
    impl()
        .current_resource_update_controller->DiscardUploadsToEvictedResources();
  }
  return true;
}

void ThreadProxy::SendManagedMemoryStats() {
  DCHECK(IsImplThread());
  if (!impl().layer_tree_host_impl)
    return;
  if (!impl().contents_texture_manager)
    return;

  // If we are using impl-side painting, then SendManagedMemoryStats is called
  // directly after the tile manager's manage function, and doesn't need to
  // interact with main thread's layer tree.
  if (impl().layer_tree_host_impl->settings().impl_side_painting)
    return;

  impl().layer_tree_host_impl->SendManagedMemoryStats(
      impl().contents_texture_manager->MemoryVisibleBytes(),
      impl().contents_texture_manager->MemoryVisibleAndNearbyBytes(),
      impl().contents_texture_manager->MemoryUseBytes());
}

bool ThreadProxy::IsInsideDraw() { return impl().inside_draw; }

void ThreadProxy::SetNeedsRedraw(const gfx::Rect& damage_rect) {
  TRACE_EVENT0("cc", "ThreadProxy::SetNeedsRedraw");
  DCHECK(IsMainThread());
  Proxy::ImplThreadTaskRunner()->PostTask(
      FROM_HERE,
      base::Bind(&ThreadProxy::SetNeedsRedrawRectOnImplThread,
                 impl_thread_weak_ptr_,
                 damage_rect));
}

void ThreadProxy::SetNextCommitWaitsForActivation() {
  DCHECK(IsMainThread());
  DCHECK(!blocked_main().main_thread_inside_commit);
  blocked_main().commit_waits_for_activation = true;
}

void ThreadProxy::SetDeferCommits(bool defer_commits) {
  DCHECK(IsMainThread());
  DCHECK_NE(main().defer_commits, defer_commits);
  main().defer_commits = defer_commits;

  if (main().defer_commits)
    TRACE_EVENT_ASYNC_BEGIN0("cc", "ThreadProxy::SetDeferCommits", this);
  else
    TRACE_EVENT_ASYNC_END0("cc", "ThreadProxy::SetDeferCommits", this);

  if (!main().defer_commits && main().pending_deferred_commit)
    Proxy::MainThreadTaskRunner()->PostTask(
        FROM_HERE,
        base::Bind(&ThreadProxy::BeginMainFrame,
                   main_thread_weak_ptr_,
                   base::Passed(&main().pending_deferred_commit)));
}

bool ThreadProxy::CommitRequested() const {
  DCHECK(IsMainThread());
  return main().commit_requested;
}

bool ThreadProxy::BeginMainFrameRequested() const {
  DCHECK(IsMainThread());
  return main().commit_request_sent_to_impl_thread;
}

void ThreadProxy::SetNeedsRedrawOnImplThread() {
  TRACE_EVENT0("cc", "ThreadProxy::SetNeedsRedrawOnImplThread");
  DCHECK(IsImplThread());
  impl().scheduler->SetNeedsRedraw();
}

void ThreadProxy::SetNeedsManageTilesOnImplThread() {
  DCHECK(IsImplThread());
  impl().scheduler->SetNeedsManageTiles();
}

void ThreadProxy::SetNeedsRedrawRectOnImplThread(const gfx::Rect& damage_rect) {
  DCHECK(IsImplThread());
  impl().layer_tree_host_impl->SetViewportDamage(damage_rect);
  SetNeedsRedrawOnImplThread();
}

void ThreadProxy::SetSwapUsedIncompleteTileOnImplThread(
    bool used_incomplete_tile) {
  DCHECK(IsImplThread());
  if (used_incomplete_tile) {
    TRACE_EVENT_INSTANT0("cc",
                         "ThreadProxy::SetSwapUsedIncompleteTileOnImplThread",
                         TRACE_EVENT_SCOPE_THREAD);
  }
  impl().scheduler->SetSwapUsedIncompleteTile(used_incomplete_tile);
}

void ThreadProxy::DidInitializeVisibleTileOnImplThread() {
  TRACE_EVENT0("cc", "ThreadProxy::DidInitializeVisibleTileOnImplThread");
  DCHECK(IsImplThread());
  impl().scheduler->SetNeedsRedraw();
}

void ThreadProxy::MainThreadHasStoppedFlinging() {
  DCHECK(IsMainThread());
  Proxy::ImplThreadTaskRunner()->PostTask(
      FROM_HERE,
      base::Bind(&ThreadProxy::MainThreadHasStoppedFlingingOnImplThread,
                 impl_thread_weak_ptr_));
}

void ThreadProxy::MainThreadHasStoppedFlingingOnImplThread() {
  DCHECK(IsImplThread());
  impl().layer_tree_host_impl->MainThreadHasStoppedFlinging();
}

void ThreadProxy::NotifyInputThrottledUntilCommit() {
  DCHECK(IsMainThread());
  Proxy::ImplThreadTaskRunner()->PostTask(
      FROM_HERE,
      base::Bind(&ThreadProxy::SetInputThrottledUntilCommitOnImplThread,
                 impl_thread_weak_ptr_,
                 true));
}

void ThreadProxy::SetInputThrottledUntilCommitOnImplThread(bool is_throttled) {
  DCHECK(IsImplThread());
  if (is_throttled == impl().input_throttled_until_commit)
    return;
  impl().input_throttled_until_commit = is_throttled;
  RenewTreePriority();
}

LayerTreeHost* ThreadProxy::layer_tree_host() {
  return blocked_main().layer_tree_host;
}

const LayerTreeHost* ThreadProxy::layer_tree_host() const {
  return blocked_main().layer_tree_host;
}

ThreadProxy::MainThreadOnly& ThreadProxy::main() {
  DCHECK(IsMainThread());
  return main_thread_only_vars_unsafe_;
}
const ThreadProxy::MainThreadOnly& ThreadProxy::main() const {
  DCHECK(IsMainThread());
  return main_thread_only_vars_unsafe_;
}

ThreadProxy::MainThreadOrBlockedMainThread& ThreadProxy::blocked_main() {
  DCHECK(IsMainThread() || IsMainThreadBlocked());
  return main_thread_or_blocked_vars_unsafe_;
}

const ThreadProxy::MainThreadOrBlockedMainThread& ThreadProxy::blocked_main()
    const {
  DCHECK(IsMainThread() || IsMainThreadBlocked());
  return main_thread_or_blocked_vars_unsafe_;
}

ThreadProxy::CompositorThreadOnly& ThreadProxy::impl() {
  DCHECK(IsImplThread());
  return compositor_thread_vars_unsafe_;
}

const ThreadProxy::CompositorThreadOnly& ThreadProxy::impl() const {
  DCHECK(IsImplThread());
  return compositor_thread_vars_unsafe_;
}

void ThreadProxy::Start() {
  DCHECK(IsMainThread());
  DCHECK(Proxy::HasImplThread());

  // Create LayerTreeHostImpl.
  DebugScopedSetMainThreadBlocked main_thread_blocked(this);
  CompletionEvent completion;
  Proxy::ImplThreadTaskRunner()->PostTask(
      FROM_HERE,
      base::Bind(&ThreadProxy::InitializeImplOnImplThread,
                 base::Unretained(this),
                 &completion));
  completion.Wait();

  main_thread_weak_ptr_ = main().weak_factory.GetWeakPtr();

  main().started = true;
}

void ThreadProxy::Stop() {
  TRACE_EVENT0("cc", "ThreadProxy::Stop");
  DCHECK(IsMainThread());
  DCHECK(main().started);

  // Synchronously finishes pending GL operations and deletes the impl.
  // The two steps are done as separate post tasks, so that tasks posted
  // by the GL implementation due to the Finish can be executed by the
  // renderer before shutting it down.
  {
    DebugScopedSetMainThreadBlocked main_thread_blocked(this);

    CompletionEvent completion;
    Proxy::ImplThreadTaskRunner()->PostTask(
        FROM_HERE,
        base::Bind(&ThreadProxy::FinishGLOnImplThread,
                   impl_thread_weak_ptr_,
                   &completion));
    completion.Wait();
  }
  {
    DebugScopedSetMainThreadBlocked main_thread_blocked(this);

    CompletionEvent completion;
    Proxy::ImplThreadTaskRunner()->PostTask(
        FROM_HERE,
        base::Bind(&ThreadProxy::LayerTreeHostClosedOnImplThread,
                   impl_thread_weak_ptr_,
                   &completion));
    completion.Wait();
  }

  main().weak_factory.InvalidateWeakPtrs();
  blocked_main().layer_tree_host = NULL;
  main().started = false;
}

void ThreadProxy::ForceSerializeOnSwapBuffers() {
  DebugScopedSetMainThreadBlocked main_thread_blocked(this);
  CompletionEvent completion;
  Proxy::ImplThreadTaskRunner()->PostTask(
      FROM_HERE,
      base::Bind(&ThreadProxy::ForceSerializeOnSwapBuffersOnImplThread,
                 impl_thread_weak_ptr_,
                 &completion));
  completion.Wait();
}

void ThreadProxy::ForceSerializeOnSwapBuffersOnImplThread(
    CompletionEvent* completion) {
  if (impl().layer_tree_host_impl->renderer())
    impl().layer_tree_host_impl->renderer()->DoNoOp();
  completion->Signal();
}

void ThreadProxy::SetDebugState(const LayerTreeDebugState& debug_state) {
  Proxy::ImplThreadTaskRunner()->PostTask(
      FROM_HERE,
      base::Bind(&ThreadProxy::SetDebugStateOnImplThread,
                 impl_thread_weak_ptr_,
                 debug_state));
}

void ThreadProxy::SetDebugStateOnImplThread(
    const LayerTreeDebugState& debug_state) {
  DCHECK(IsImplThread());
  impl().scheduler->SetContinuousPainting(debug_state.continuous_painting);
}

void ThreadProxy::FinishAllRenderingOnImplThread(CompletionEvent* completion) {
  TRACE_EVENT0("cc", "ThreadProxy::FinishAllRenderingOnImplThread");
  DCHECK(IsImplThread());
  impl().layer_tree_host_impl->FinishAllRendering();
  completion->Signal();
}

void ThreadProxy::ScheduledActionSendBeginMainFrame() {
  TRACE_EVENT0("cc", "ThreadProxy::ScheduledActionSendBeginMainFrame");
  scoped_ptr<BeginMainFrameAndCommitState> begin_main_frame_state(
      new BeginMainFrameAndCommitState);
  begin_main_frame_state->monotonic_frame_begin_time =
      impl().layer_tree_host_impl->CurrentFrameTimeTicks();
  begin_main_frame_state->scroll_info =
      impl().layer_tree_host_impl->ProcessScrollDeltas();

  if (!impl().layer_tree_host_impl->settings().impl_side_painting) {
    DCHECK_GT(impl().layer_tree_host_impl->memory_allocation_limit_bytes(), 0u);
  }
  begin_main_frame_state->memory_allocation_limit_bytes =
      impl().layer_tree_host_impl->memory_allocation_limit_bytes();
  begin_main_frame_state->memory_allocation_priority_cutoff =
      impl().layer_tree_host_impl->memory_allocation_priority_cutoff();
  begin_main_frame_state->evicted_ui_resources =
      impl().layer_tree_host_impl->EvictedUIResourcesExist();
  Proxy::MainThreadTaskRunner()->PostTask(
      FROM_HERE,
      base::Bind(&ThreadProxy::BeginMainFrame,
                 main_thread_weak_ptr_,
                 base::Passed(&begin_main_frame_state)));
  devtools_instrumentation::DidRequestMainThreadFrame(
      impl().layer_tree_host_id);
  if (impl().begin_main_frame_sent_completion_event) {
    impl().begin_main_frame_sent_completion_event->Signal();
    impl().begin_main_frame_sent_completion_event = NULL;
  }
  impl().timing_history.DidBeginMainFrame();
}

void ThreadProxy::BeginMainFrame(
    scoped_ptr<BeginMainFrameAndCommitState> begin_main_frame_state) {
  TRACE_EVENT0("cc", "ThreadProxy::BeginMainFrame");
  TRACE_EVENT_SYNTHETIC_DELAY_BEGIN("cc.BeginMainFrame");
  DCHECK(IsMainThread());

  if (!layer_tree_host())
    return;

  if (main().defer_commits) {
    main().pending_deferred_commit = begin_main_frame_state.Pass();
    layer_tree_host()->DidDeferCommit();
    TRACE_EVENT_INSTANT0(
        "cc", "EarlyOut_DeferCommits", TRACE_EVENT_SCOPE_THREAD);
    return;
  }

  // If the commit finishes, LayerTreeHost will transfer its swap promises to
  // LayerTreeImpl. The destructor of SwapPromiseChecker checks LayerTressHost's
  // swap promises.
  SwapPromiseChecker swap_promise_checker(layer_tree_host());

  // Do not notify the impl thread of commit requests that occur during
  // the apply/animate/layout part of the BeginMainFrameAndCommit process since
  // those commit requests will get painted immediately. Once we have done
  // the paint, main().commit_requested will be set to false to allow new commit
  // requests to be scheduled.
  main().commit_requested = true;
  main().commit_request_sent_to_impl_thread = true;

  // On the other hand, the AnimationRequested flag needs to be cleared
  // here so that any animation requests generated by the apply or animate
  // callbacks will trigger another frame.
  main().animate_requested = false;

  if (!main().in_composite_and_readback && !layer_tree_host()->visible()) {
    main().commit_requested = false;
    main().commit_request_sent_to_impl_thread = false;

    TRACE_EVENT_INSTANT0("cc", "EarlyOut_NotVisible", TRACE_EVENT_SCOPE_THREAD);
    bool did_handle = false;
    Proxy::ImplThreadTaskRunner()->PostTask(
        FROM_HERE,
        base::Bind(&ThreadProxy::BeginMainFrameAbortedOnImplThread,
                   impl_thread_weak_ptr_,
                   did_handle));
    return;
  }

  if (begin_main_frame_state) {
    layer_tree_host()->ApplyScrollAndScale(
        *begin_main_frame_state->scroll_info);
  }

  layer_tree_host()->WillBeginMainFrame();

  if (begin_main_frame_state) {
    layer_tree_host()->UpdateClientAnimations(
        begin_main_frame_state->monotonic_frame_begin_time);
    layer_tree_host()->AnimateLayers(
        begin_main_frame_state->monotonic_frame_begin_time);
    blocked_main().last_monotonic_frame_begin_time =
        begin_main_frame_state->monotonic_frame_begin_time;
  }

  // Unlink any backings that the impl thread has evicted, so that we know to
  // re-paint them in UpdateLayers.
  if (blocked_main().contents_texture_manager()) {
    blocked_main().contents_texture_manager()->UnlinkAndClearEvictedBackings();

    if (begin_main_frame_state) {
      blocked_main().contents_texture_manager()->SetMaxMemoryLimitBytes(
          begin_main_frame_state->memory_allocation_limit_bytes);
      blocked_main().contents_texture_manager()->SetExternalPriorityCutoff(
          begin_main_frame_state->memory_allocation_priority_cutoff);
    }
  }

  // Recreate all UI resources if there were evicted UI resources when the impl
  // thread initiated the commit.
  bool evicted_ui_resources = begin_main_frame_state
                                  ? begin_main_frame_state->evicted_ui_resources
                                  : false;
  if (evicted_ui_resources)
    layer_tree_host()->RecreateUIResources();

  layer_tree_host()->Layout();
  TRACE_EVENT_SYNTHETIC_DELAY_END("cc.BeginMainFrame");

  // Clear the commit flag after updating animations and layout here --- objects
  // that only layout when painted will trigger another SetNeedsCommit inside
  // UpdateLayers.
  main().commit_requested = false;
  main().commit_request_sent_to_impl_thread = false;
  bool can_cancel_this_commit = main().can_cancel_commit &&
                                !main().in_composite_and_readback &&
                                !evicted_ui_resources;
  main().can_cancel_commit = true;

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

  bool updated = layer_tree_host()->UpdateLayers(queue.get());

  // Once single buffered layers are committed, they cannot be modified until
  // they are drawn by the impl thread.
  main().textures_acquired = false;

  layer_tree_host()->WillCommit();

  // Before calling animate, we set main().animate_requested to false. If it is
  // true now, it means SetNeedAnimate was called again, but during a state when
  // main().commit_request_sent_to_impl_thread = true. We need to force that
  // call to happen again now so that the commit request is sent to the impl
  // thread.
  if (main().animate_requested) {
    // Forces SetNeedsAnimate to consider posting a commit task.
    main().animate_requested = false;
    SetNeedsAnimate();
  }

  if (!updated && can_cancel_this_commit) {
    TRACE_EVENT_INSTANT0("cc", "EarlyOut_NoUpdates", TRACE_EVENT_SCOPE_THREAD);
    bool did_handle = true;
    Proxy::ImplThreadTaskRunner()->PostTask(
        FROM_HERE,
        base::Bind(&ThreadProxy::BeginMainFrameAbortedOnImplThread,
                   impl_thread_weak_ptr_,
                   did_handle));

    // Although the commit is internally aborted, this is because it has been
    // detected to be a no-op.  From the perspective of an embedder, this commit
    // went through, and input should no longer be throttled, etc.
    layer_tree_host()->CommitComplete();
    layer_tree_host()->DidBeginMainFrame();
    return;
  }

  scoped_refptr<ContextProvider> offscreen_context_provider;
  if (main().renderer_capabilities_main_thread_copy.using_offscreen_context3d &&
      layer_tree_host()->needs_offscreen_context()) {
    offscreen_context_provider =
        layer_tree_host()->client()->OffscreenContextProvider();
    if (offscreen_context_provider.get())
      main().created_offscreen_context_provider = true;
  }

  // Notify the impl thread that the main thread is ready to commit. This will
  // begin the commit process, which is blocking from the main thread's
  // point of view, but asynchronously performed on the impl thread,
  // coordinated by the Scheduler.
  {
    TRACE_EVENT0("cc", "ThreadProxy::BeginMainFrame::commit");

    DebugScopedSetMainThreadBlocked main_thread_blocked(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;

    CompletionEvent completion;
    Proxy::ImplThreadTaskRunner()->PostTask(
        FROM_HERE,
        base::Bind(&ThreadProxy::StartCommitOnImplThread,
                   impl_thread_weak_ptr_,
                   &completion,
                   queue.release(),
                   offscreen_context_provider));
    completion.Wait();

    RenderingStatsInstrumentation* stats_instrumentation =
        layer_tree_host()->rendering_stats_instrumentation();
    BenchmarkInstrumentation::IssueMainThreadRenderingStatsEvent(
        stats_instrumentation->main_thread_rendering_stats());
    stats_instrumentation->AccumulateAndClearMainThreadStats();
  }

  layer_tree_host()->CommitComplete();
  layer_tree_host()->DidBeginMainFrame();
}

void ThreadProxy::StartCommitOnImplThread(
    CompletionEvent* completion,
    ResourceUpdateQueue* raw_queue,
    scoped_refptr<ContextProvider> offscreen_context_provider) {
  TRACE_EVENT0("cc", "ThreadProxy::StartCommitOnImplThread");
  DCHECK(!impl().commit_completion_event);
  DCHECK(IsImplThread() && IsMainThreadBlocked());
  DCHECK(impl().scheduler);
  DCHECK(impl().scheduler->CommitPending());

  if (!impl().layer_tree_host_impl) {
    TRACE_EVENT_INSTANT0(
        "cc", "EarlyOut_NoLayerTree", TRACE_EVENT_SCOPE_THREAD);
    completion->Signal();
    return;
  }

  // Ideally, we should inform to impl thread when BeginMainFrame is started.
  // But, we can avoid a PostTask in here.
  impl().scheduler->NotifyBeginMainFrameStarted();

  scoped_ptr<ResourceUpdateQueue> queue(raw_queue);

  if (offscreen_context_provider.get())
    offscreen_context_provider->BindToCurrentThread();
  impl().layer_tree_host_impl->SetOffscreenContextProvider(
      offscreen_context_provider);

  if (impl().contents_texture_manager) {
    DCHECK_EQ(impl().contents_texture_manager,
              blocked_main().contents_texture_manager());
  } else {
    // Cache this pointer that was created on the main thread side to avoid a
    // data race between creating it and using it on the compositor thread.
    impl().contents_texture_manager = blocked_main().contents_texture_manager();
  }

  if (impl().contents_texture_manager) {
    if (impl().contents_texture_manager->LinkedEvictedBackingsExist()) {
      // Clear any uploads we were making to textures linked to evicted
      // resources
      queue->ClearUploadsToEvictedResources();
      // Some textures in the layer tree are invalid. Kick off another commit
      // to fill them again.
      SetNeedsCommitOnImplThread();
    }

    impl().contents_texture_manager->PushTexturePrioritiesToBackings();
  }

  impl().commit_completion_event = completion;
  impl().current_resource_update_controller = ResourceUpdateController::Create(
      this,
      Proxy::ImplThreadTaskRunner(),
      queue.Pass(),
      impl().layer_tree_host_impl->resource_provider());
  impl().current_resource_update_controller->PerformMoreUpdates(
      impl().scheduler->AnticipatedDrawTime());
}

void ThreadProxy::BeginMainFrameAbortedOnImplThread(bool did_handle) {
  TRACE_EVENT0("cc", "ThreadProxy::BeginMainFrameAbortedOnImplThread");
  DCHECK(IsImplThread());
  DCHECK(impl().scheduler);
  DCHECK(impl().scheduler->CommitPending());
  DCHECK(!impl().layer_tree_host_impl->pending_tree());

  if (did_handle)
    SetInputThrottledUntilCommitOnImplThread(false);
  impl().layer_tree_host_impl->BeginMainFrameAborted(did_handle);
  impl().scheduler->BeginMainFrameAborted(did_handle);
}

void ThreadProxy::ScheduledActionCommit() {
  TRACE_EVENT0("cc", "ThreadProxy::ScheduledActionCommit");
  DCHECK(IsImplThread());
  DCHECK(IsMainThreadBlocked());
  DCHECK(impl().commit_completion_event);
  DCHECK(impl().current_resource_update_controller);

  // Complete all remaining texture updates.
  impl().current_resource_update_controller->Finalize();
  impl().current_resource_update_controller.reset();

  if (impl().animations_frozen_until_next_draw) {
    impl().animation_freeze_time =
        std::max(impl().animation_freeze_time,
                 blocked_main().last_monotonic_frame_begin_time);
  }

  blocked_main().main_thread_inside_commit = true;
  impl().layer_tree_host_impl->BeginCommit();
  layer_tree_host()->BeginCommitOnImplThread(impl().layer_tree_host_impl.get());
  layer_tree_host()->FinishCommitOnImplThread(
      impl().layer_tree_host_impl.get());
  blocked_main().main_thread_inside_commit = false;

  bool hold_commit = layer_tree_host()->settings().impl_side_painting &&
                     blocked_main().commit_waits_for_activation;
  blocked_main().commit_waits_for_activation = false;

  if (hold_commit) {
    // For some layer types in impl-side painting, the commit is held until
    // the pending tree is activated.  It's also possible that the
    // pending tree has already activated if there was no work to be done.
    TRACE_EVENT_INSTANT0("cc", "HoldCommit", TRACE_EVENT_SCOPE_THREAD);
    impl().completion_event_for_commit_held_on_tree_activation =
        impl().commit_completion_event;
    impl().commit_completion_event = NULL;
  } else {
    impl().commit_completion_event->Signal();
    impl().commit_completion_event = NULL;
  }

  // Delay this step until afer the main thread has been released as it's
  // often a good bit of work to update the tree and prepare the new frame.
  impl().layer_tree_host_impl->CommitComplete();

  SetInputThrottledUntilCommitOnImplThread(false);

  UpdateBackgroundAnimateTicking();

  impl().next_frame_is_newly_committed_frame = true;

  impl().timing_history.DidCommit();

  // SetVisible kicks off the next scheduler action, so this must be last.
  impl().scheduler->SetVisible(impl().layer_tree_host_impl->visible());
}

void ThreadProxy::ScheduledActionUpdateVisibleTiles() {
  TRACE_EVENT0("cc", "ThreadProxy::ScheduledActionUpdateVisibleTiles");
  DCHECK(IsImplThread());
  impl().layer_tree_host_impl->UpdateVisibleTiles();
}

void ThreadProxy::ScheduledActionActivatePendingTree() {
  TRACE_EVENT0("cc", "ThreadProxy::ScheduledActionActivatePendingTree");
  DCHECK(IsImplThread());
  impl().layer_tree_host_impl->ActivatePendingTree();
}

void ThreadProxy::ScheduledActionBeginOutputSurfaceCreation() {
  TRACE_EVENT0("cc", "ThreadProxy::ScheduledActionBeginOutputSurfaceCreation");
  DCHECK(IsImplThread());
  Proxy::MainThreadTaskRunner()->PostTask(
      FROM_HERE,
      base::Bind(&ThreadProxy::CreateAndInitializeOutputSurface,
                 main_thread_weak_ptr_));
}

DrawSwapReadbackResult ThreadProxy::DrawSwapReadbackInternal(
    bool forced_draw,
    bool swap_requested,
    bool readback_requested) {
  TRACE_EVENT_SYNTHETIC_DELAY("cc.DrawAndSwap");
  DrawSwapReadbackResult result;

  DCHECK(IsImplThread());
  DCHECK(impl().layer_tree_host_impl.get());

  impl().timing_history.DidStartDrawing();
  base::TimeDelta draw_duration_estimate = DrawDurationEstimate();
  base::AutoReset<bool> mark_inside(&impl().inside_draw, true);

  // Advance our animations.
  base::TimeTicks monotonic_time;
  if (impl().animations_frozen_until_next_draw)
    monotonic_time = impl().animation_freeze_time;
  else
    monotonic_time = impl().layer_tree_host_impl->CurrentFrameTimeTicks();

  // TODO(enne): This should probably happen post-animate.
  if (impl().layer_tree_host_impl->pending_tree())
    impl().layer_tree_host_impl->pending_tree()->UpdateDrawProperties();
  impl().layer_tree_host_impl->Animate(monotonic_time);

  // This method is called on a forced draw, regardless of whether we are able
  // to produce a frame, as the calling site on main thread is blocked until its
  // request completes, and we signal completion here. If CanDraw() is false, we
  // will indicate success=false to the caller, but we must still signal
  // completion to avoid deadlock.

  // 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.

  bool drawing_for_readback = readback_requested && !!impl().readback_request;
  bool can_do_readback =
      impl().layer_tree_host_impl->renderer()->CanReadPixels();

  LayerTreeHostImpl::FrameData frame;
  bool draw_frame = false;

  if (impl().layer_tree_host_impl->CanDraw()) {
    if (!drawing_for_readback || can_do_readback) {
      // If it is for a readback, make sure we draw the portion being read back.
      gfx::Rect readback_rect;
      if (drawing_for_readback)
        readback_rect = impl().readback_request->rect;

      result.draw_result =
          impl().layer_tree_host_impl->PrepareToDraw(&frame, readback_rect);
      draw_frame = forced_draw ||
                   result.draw_result == DrawSwapReadbackResult::DRAW_SUCCESS;
    } else {
      result.draw_result = DrawSwapReadbackResult::DRAW_ABORTED_CANT_READBACK;
    }
  } else {
    result.draw_result = DrawSwapReadbackResult::DRAW_ABORTED_CANT_DRAW;
  }

  if (draw_frame) {
    impl().layer_tree_host_impl->DrawLayers(
        &frame, impl().scheduler->LastBeginImplFrameTime());
    result.draw_result = DrawSwapReadbackResult::DRAW_SUCCESS;
    impl().animations_frozen_until_next_draw = false;
  } else if (result.draw_result ==
                 DrawSwapReadbackResult::DRAW_ABORTED_CHECKERBOARD_ANIMATIONS &&
             !impl().layer_tree_host_impl->settings().impl_side_painting) {
    // Without impl-side painting, the animated layer that is checkerboarding
    // will continue to checkerboard until the next commit. If this layer
    // continues to move during the commit, it may continue to checkerboard
    // after the commit since the region rasterized during the commit will not
    // match the region that is currently visible; eventually this
    // checkerboarding will be displayed when we force a draw. To avoid this,
    // we freeze animations until we successfully draw.
    impl().animations_frozen_until_next_draw = true;
    impl().animation_freeze_time = monotonic_time;
  } else {
    DCHECK_NE(DrawSwapReadbackResult::DRAW_SUCCESS, result.draw_result);
  }
  impl().layer_tree_host_impl->DidDrawAllLayers(frame);

  bool start_ready_animations = draw_frame;
  impl().layer_tree_host_impl->UpdateAnimationState(start_ready_animations);

  // Check for a pending CompositeAndReadback.
  if (drawing_for_readback) {
    DCHECK(!swap_requested);
    result.did_readback = false;
    if (draw_frame) {
      if (!impl().layer_tree_host_impl->IsContextLost()) {
        impl().layer_tree_host_impl->Readback(impl().readback_request->pixels,
                                              impl().readback_request->rect);
        result.did_readback = true;
      } else {
        result.draw_result = DrawSwapReadbackResult::DRAW_ABORTED_CONTEXT_LOST;
      }
    }
    impl().readback_request->success = result.did_readback;
    impl().readback_request->completion.Signal();
    impl().readback_request = NULL;
  } else if (draw_frame) {
    DCHECK(swap_requested);
    result.did_swap = impl().layer_tree_host_impl->SwapBuffers(frame);

    // We don't know if we have incomplete tiles if we didn't actually swap.
    if (result.did_swap) {
      DCHECK(!frame.has_no_damage);
      SetSwapUsedIncompleteTileOnImplThread(frame.contains_incomplete_tile);
    }
  }

  // Tell the main thread that the the newly-commited frame was drawn.
  if (impl().next_frame_is_newly_committed_frame) {
    impl().next_frame_is_newly_committed_frame = false;
    Proxy::MainThreadTaskRunner()->PostTask(
        FROM_HERE,
        base::Bind(&ThreadProxy::DidCommitAndDrawFrame, main_thread_weak_ptr_));
  }

  if (draw_frame)
    CheckOutputSurfaceStatusOnImplThread();

  if (result.draw_result == DrawSwapReadbackResult::DRAW_SUCCESS) {
    base::TimeDelta draw_duration = impl().timing_history.DidFinishDrawing();

    base::TimeDelta draw_duration_overestimate;
    base::TimeDelta draw_duration_underestimate;
    if (draw_duration > draw_duration_estimate)
      draw_duration_underestimate = draw_duration - draw_duration_estimate;
    else
      draw_duration_overestimate = draw_duration_estimate - draw_duration;
    UMA_HISTOGRAM_CUSTOM_TIMES("Renderer.DrawDuration",
                               draw_duration,
                               base::TimeDelta::FromMilliseconds(1),
                               base::TimeDelta::FromMilliseconds(100),
                               50);
    UMA_HISTOGRAM_CUSTOM_TIMES("Renderer.DrawDurationUnderestimate",
                               draw_duration_underestimate,
                               base::TimeDelta::FromMilliseconds(1),
                               base::TimeDelta::FromMilliseconds(100),
                               50);
    UMA_HISTOGRAM_CUSTOM_TIMES("Renderer.DrawDurationOverestimate",
                               draw_duration_overestimate,
                               base::TimeDelta::FromMilliseconds(1),
                               base::TimeDelta::FromMilliseconds(100),
                               50);
  }

  DCHECK_NE(DrawSwapReadbackResult::INVALID_RESULT, result.draw_result);
  return result;
}

void ThreadProxy::AcquireLayerTextures() {
  // Called when the main thread needs to modify a layer texture that is used
  // directly by the compositor.
  // This method will block until the next compositor draw if there is a
  // previously committed frame that is still undrawn. This is necessary to
  // ensure that the main thread does not monopolize access to the textures.
  DCHECK(IsMainThread());

  if (main().textures_acquired)
    return;

  TRACE_EVENT0("cc", "ThreadProxy::AcquireLayerTextures");
  DebugScopedSetMainThreadBlocked main_thread_blocked(this);
  CompletionEvent completion;
  Proxy::ImplThreadTaskRunner()->PostTask(
      FROM_HERE,
      base::Bind(&ThreadProxy::AcquireLayerTexturesForMainThreadOnImplThread,
                 impl_thread_weak_ptr_,
                 &completion));
  // Block until it is safe to write to layer textures from the main thread.
  completion.Wait();

  main().textures_acquired = true;
  main().can_cancel_commit = false;
}

void ThreadProxy::AcquireLayerTexturesForMainThreadOnImplThread(
    CompletionEvent* completion) {
  DCHECK(IsImplThread());
  DCHECK(!impl().texture_acquisition_completion_event);

  impl().texture_acquisition_completion_event = completion;
  impl().scheduler->SetMainThreadNeedsLayerTextures();
}

void ThreadProxy::ScheduledActionAcquireLayerTexturesForMainThread() {
  DCHECK(impl().texture_acquisition_completion_event);
  impl().texture_acquisition_completion_event->Signal();
  impl().texture_acquisition_completion_event = NULL;
}

void ThreadProxy::ScheduledActionManageTiles() {
  TRACE_EVENT0("cc", "ThreadProxy::ScheduledActionManageTiles");
  DCHECK(impl().layer_tree_host_impl->settings().impl_side_painting);
  impl().layer_tree_host_impl->ManageTiles();
}

DrawSwapReadbackResult ThreadProxy::ScheduledActionDrawAndSwapIfPossible() {
  TRACE_EVENT0("cc", "ThreadProxy::ScheduledActionDrawAndSwap");

  // SchedulerStateMachine::DidDrawIfPossibleCompleted isn't set up to
  // handle DRAW_ABORTED_CANT_DRAW.  Moreover, the scheduler should
  // never generate this call when it can't draw.
  DCHECK(impl().layer_tree_host_impl->CanDraw());

  bool forced_draw = false;
  bool swap_requested = true;
  bool readback_requested = false;
  return DrawSwapReadbackInternal(
      forced_draw, swap_requested, readback_requested);
}

DrawSwapReadbackResult ThreadProxy::ScheduledActionDrawAndSwapForced() {
  TRACE_EVENT0("cc", "ThreadProxy::ScheduledActionDrawAndSwapForced");
  bool forced_draw = true;
  bool swap_requested = true;
  bool readback_requested = false;
  return DrawSwapReadbackInternal(
      forced_draw, swap_requested, readback_requested);
}

DrawSwapReadbackResult ThreadProxy::ScheduledActionDrawAndReadback() {
  TRACE_EVENT0("cc", "ThreadProxy::ScheduledActionDrawAndReadback");
  bool forced_draw = true;
  bool swap_requested = false;
  bool readback_requested = true;
  return DrawSwapReadbackInternal(
      forced_draw, swap_requested, readback_requested);
}

void ThreadProxy::DidAnticipatedDrawTimeChange(base::TimeTicks time) {
  if (impl().current_resource_update_controller)
    impl().current_resource_update_controller->PerformMoreUpdates(time);
}

base::TimeDelta ThreadProxy::DrawDurationEstimate() {
  return impl().timing_history.DrawDurationEstimate();
}

base::TimeDelta ThreadProxy::BeginMainFrameToCommitDurationEstimate() {
  return impl().timing_history.BeginMainFrameToCommitDurationEstimate();
}

base::TimeDelta ThreadProxy::CommitToActivateDurationEstimate() {
  return impl().timing_history.CommitToActivateDurationEstimate();
}

void ThreadProxy::DidBeginImplFrameDeadline() {
  impl().layer_tree_host_impl->ResetCurrentFrameTimeForNextFrame();
}

void ThreadProxy::ReadyToFinalizeTextureUpdates() {
  DCHECK(IsImplThread());
  impl().scheduler->NotifyReadyToCommit();
}

void ThreadProxy::DidCommitAndDrawFrame() {
  DCHECK(IsMainThread());
  if (!layer_tree_host())
    return;
  layer_tree_host()->DidCommitAndDrawFrame();
}

void ThreadProxy::DidCompleteSwapBuffers() {
  DCHECK(IsMainThread());
  if (!layer_tree_host())
    return;
  layer_tree_host()->DidCompleteSwapBuffers();
}

void ThreadProxy::SetAnimationEvents(scoped_ptr<AnimationEventsVector> events) {
  TRACE_EVENT0("cc", "ThreadProxy::SetAnimationEvents");
  DCHECK(IsMainThread());
  if (!layer_tree_host())
    return;
  layer_tree_host()->SetAnimationEvents(events.Pass());
}

void ThreadProxy::CreateAndInitializeOutputSurface() {
  TRACE_EVENT0("cc", "ThreadProxy::CreateAndInitializeOutputSurface");
  DCHECK(IsMainThread());

  // Check that output surface has not been recreated by CompositeAndReadback
  // after this task is posted but before it is run.
  bool has_initialized_output_surface = true;
  {
    CompletionEvent completion;
    Proxy::ImplThreadTaskRunner()->PostTask(
        FROM_HERE,
        base::Bind(&ThreadProxy::HasInitializedOutputSurfaceOnImplThread,
                   impl_thread_weak_ptr_,
                   &completion,
                   &has_initialized_output_surface));
    completion.Wait();
  }
  if (has_initialized_output_surface)
    return;

  layer_tree_host()->DidLoseOutputSurface();
  main().output_surface_creation_callback.Reset(
      base::Bind(&ThreadProxy::DoCreateAndInitializeOutputSurface,
                 base::Unretained(this)));
  main().output_surface_creation_callback.callback().Run();
}

void ThreadProxy::HasInitializedOutputSurfaceOnImplThread(
    CompletionEvent* completion,
    bool* has_initialized_output_surface) {
  DCHECK(IsImplThread());
  *has_initialized_output_surface =
      impl().scheduler->HasInitializedOutputSurface();
  completion->Signal();
}

void ThreadProxy::InitializeImplOnImplThread(CompletionEvent* completion) {
  TRACE_EVENT0("cc", "ThreadProxy::InitializeImplOnImplThread");
  DCHECK(IsImplThread());
  impl().layer_tree_host_impl =
      layer_tree_host()->CreateLayerTreeHostImpl(this);
  const LayerTreeSettings& settings = layer_tree_host()->settings();
  SchedulerSettings scheduler_settings;
  scheduler_settings.main_frame_before_draw_enabled =
      settings.main_frame_before_draw_enabled;
  scheduler_settings.main_frame_before_activation_enabled =
      settings.main_frame_before_activation_enabled;
  scheduler_settings.impl_side_painting = settings.impl_side_painting;
  scheduler_settings.timeout_and_draw_when_animation_checkerboards =
      settings.timeout_and_draw_when_animation_checkerboards;
  scheduler_settings.maximum_number_of_failed_draws_before_draw_is_forced_ =
      settings.maximum_number_of_failed_draws_before_draw_is_forced_;
  scheduler_settings.using_synchronous_renderer_compositor =
      settings.using_synchronous_renderer_compositor;
  scheduler_settings.throttle_frame_production =
      settings.throttle_frame_production;
  impl().scheduler = Scheduler::Create(this,
                                       scheduler_settings,
                                       impl().layer_tree_host_id,
                                       ImplThreadTaskRunner());
  impl().scheduler->SetVisible(impl().layer_tree_host_impl->visible());

  impl_thread_weak_ptr_ = impl().weak_factory.GetWeakPtr();
  completion->Signal();
}

void ThreadProxy::InitializeOutputSurfaceOnImplThread(
    CompletionEvent* completion,
    scoped_ptr<OutputSurface> output_surface,
    scoped_refptr<ContextProvider> offscreen_context_provider,
    bool* success,
    RendererCapabilities* capabilities) {
  TRACE_EVENT0("cc", "ThreadProxy::InitializeOutputSurfaceOnImplThread");
  DCHECK(IsImplThread());
  DCHECK(IsMainThreadBlocked());
  DCHECK(success);
  DCHECK(capabilities);

  layer_tree_host()->DeleteContentsTexturesOnImplThread(
      impl().layer_tree_host_impl->resource_provider());

  *success =
      impl().layer_tree_host_impl->InitializeRenderer(output_surface.Pass());

  if (*success) {
    *capabilities = impl()
                        .layer_tree_host_impl->GetRendererCapabilities()
                        .MainThreadCapabilities();
    impl().scheduler->DidCreateAndInitializeOutputSurface();
  } else if (offscreen_context_provider.get()) {
    if (offscreen_context_provider->BindToCurrentThread())
      offscreen_context_provider->VerifyContexts();
    offscreen_context_provider = NULL;
  }

  impl().layer_tree_host_impl->SetOffscreenContextProvider(
      offscreen_context_provider);

  completion->Signal();
}

void ThreadProxy::FinishGLOnImplThread(CompletionEvent* completion) {
  TRACE_EVENT0("cc", "ThreadProxy::FinishGLOnImplThread");
  DCHECK(IsImplThread());
  if (impl().layer_tree_host_impl->resource_provider())
    impl().layer_tree_host_impl->resource_provider()->Finish();
  completion->Signal();
}

void ThreadProxy::LayerTreeHostClosedOnImplThread(CompletionEvent* completion) {
  TRACE_EVENT0("cc", "ThreadProxy::LayerTreeHostClosedOnImplThread");
  DCHECK(IsImplThread());
  layer_tree_host()->DeleteContentsTexturesOnImplThread(
      impl().layer_tree_host_impl->resource_provider());
  impl().current_resource_update_controller.reset();
  impl().layer_tree_host_impl->SetNeedsBeginImplFrame(false);
  impl().scheduler.reset();
  impl().layer_tree_host_impl.reset();
  impl().weak_factory.InvalidateWeakPtrs();
  impl().contents_texture_manager = NULL;
  completion->Signal();
}

size_t ThreadProxy::MaxPartialTextureUpdates() const {
  return ResourceUpdateController::MaxPartialTextureUpdates();
}

ThreadProxy::BeginMainFrameAndCommitState::BeginMainFrameAndCommitState()
    : memory_allocation_limit_bytes(0),
      memory_allocation_priority_cutoff(0),
      evicted_ui_resources(false) {}

ThreadProxy::BeginMainFrameAndCommitState::~BeginMainFrameAndCommitState() {}

scoped_ptr<base::Value> ThreadProxy::AsValue() const {
  scoped_ptr<base::DictionaryValue> state(new base::DictionaryValue());

  CompletionEvent completion;
  {
    DebugScopedSetMainThreadBlocked main_thread_blocked(
        const_cast<ThreadProxy*>(this));
    Proxy::ImplThreadTaskRunner()->PostTask(
        FROM_HERE,
        base::Bind(&ThreadProxy::AsValueOnImplThread,
                   impl_thread_weak_ptr_,
                   &completion,
                   state.get()));
    completion.Wait();
  }
  return state.PassAs<base::Value>();
}

void ThreadProxy::AsValueOnImplThread(CompletionEvent* completion,
                                      base::DictionaryValue* state) const {
  state->Set("layer_tree_host_impl",
             impl().layer_tree_host_impl->AsValue().release());
  completion->Signal();
}

bool ThreadProxy::CommitPendingForTesting() {
  DCHECK(IsMainThread());
  CommitPendingRequest commit_pending_request;
  {
    DebugScopedSetMainThreadBlocked main_thread_blocked(this);
    Proxy::ImplThreadTaskRunner()->PostTask(
        FROM_HERE,
        base::Bind(&ThreadProxy::CommitPendingOnImplThreadForTesting,
                   impl_thread_weak_ptr_,
                   &commit_pending_request));
    commit_pending_request.completion.Wait();
  }
  return commit_pending_request.commit_pending;
}

void ThreadProxy::CommitPendingOnImplThreadForTesting(
    CommitPendingRequest* request) {
  DCHECK(IsImplThread());
  if (impl().layer_tree_host_impl->output_surface())
    request->commit_pending = impl().scheduler->CommitPending();
  else
    request->commit_pending = false;
  request->completion.Signal();
}

scoped_ptr<base::Value> ThreadProxy::SchedulerStateAsValueForTesting() {
  if (IsImplThread())
    return impl().scheduler->StateAsValue().Pass();

  SchedulerStateRequest scheduler_state_request;
  {
    DebugScopedSetMainThreadBlocked main_thread_blocked(this);
    Proxy::ImplThreadTaskRunner()->PostTask(
        FROM_HERE,
        base::Bind(&ThreadProxy::SchedulerStateAsValueOnImplThreadForTesting,
                   impl_thread_weak_ptr_,
                   &scheduler_state_request));
    scheduler_state_request.completion.Wait();
  }
  return scheduler_state_request.state.Pass();
}

void ThreadProxy::SchedulerStateAsValueOnImplThreadForTesting(
    SchedulerStateRequest* request) {
  DCHECK(IsImplThread());
  request->state = impl().scheduler->StateAsValue();
  request->completion.Signal();
}

void ThreadProxy::RenewTreePriority() {
  DCHECK(IsImplThread());
  bool smoothness_takes_priority =
      impl().layer_tree_host_impl->pinch_gesture_active() ||
      impl().layer_tree_host_impl->page_scale_animation_active() ||
      (impl().layer_tree_host_impl->IsCurrentlyScrolling() &&
       !impl().layer_tree_host_impl->scroll_affects_scroll_handler());

  base::TimeTicks now = impl().layer_tree_host_impl->CurrentFrameTimeTicks();

  // Update expiration time if smoothness currently takes priority.
  if (smoothness_takes_priority) {
    impl().smoothness_takes_priority_expiration_time =
        now + base::TimeDelta::FromMilliseconds(
                  kSmoothnessTakesPriorityExpirationDelay * 1000);
  }

  // We use the same priority for both trees by default.
  TreePriority priority = SAME_PRIORITY_FOR_BOTH_TREES;

  // Smoothness takes priority if expiration time is in the future.
  if (impl().smoothness_takes_priority_expiration_time > now)
    priority = SMOOTHNESS_TAKES_PRIORITY;

  // New content always takes priority when the active tree has
  // evicted resources or there is an invalid viewport size.
  if (impl().layer_tree_host_impl->active_tree()->ContentsTexturesPurged() ||
      impl().layer_tree_host_impl->active_tree()->ViewportSizeInvalid() ||
      impl().layer_tree_host_impl->EvictedUIResourcesExist() ||
      impl().input_throttled_until_commit) {
    // Once we enter NEW_CONTENTS_TAKES_PRIORITY mode, visible tiles on active
    // tree might be freed. We need to set RequiresHighResToDraw to ensure that
    // high res tiles will be required to activate pending tree.
    impl().layer_tree_host_impl->active_tree()->SetRequiresHighResToDraw();
    priority = NEW_CONTENT_TAKES_PRIORITY;
  }

  impl().layer_tree_host_impl->SetTreePriority(priority);
  impl().scheduler->SetSmoothnessTakesPriority(priority ==
                                               SMOOTHNESS_TAKES_PRIORITY);

  // Notify the the client of this compositor via the output surface.
  // TODO(epenner): Route this to compositor-thread instead of output-surface
  // after GTFO refactor of compositor-thread (http://crbug/170828).
  if (impl().layer_tree_host_impl->output_surface()) {
    impl()
        .layer_tree_host_impl->output_surface()
        ->UpdateSmoothnessTakesPriority(priority == SMOOTHNESS_TAKES_PRIORITY);
  }

  base::TimeDelta delay =
      impl().smoothness_takes_priority_expiration_time - now;

  // Need to make sure a delayed task is posted when we have smoothness
  // takes priority expiration time in the future.
  if (delay <= base::TimeDelta())
    return;
  if (impl().renew_tree_priority_pending)
    return;

  Proxy::ImplThreadTaskRunner()->PostDelayedTask(
      FROM_HERE,
      base::Bind(&ThreadProxy::RenewTreePriorityOnImplThread,
                 impl_thread_weak_ptr_),
      delay);

  impl().renew_tree_priority_pending = true;
}

void ThreadProxy::RenewTreePriorityOnImplThread() {
  DCHECK(impl().renew_tree_priority_pending);
  impl().renew_tree_priority_pending = false;

  RenewTreePriority();
}

void ThreadProxy::RequestScrollbarAnimationOnImplThread(base::TimeDelta delay) {
  Proxy::ImplThreadTaskRunner()->PostDelayedTask(
      FROM_HERE,
      base::Bind(&ThreadProxy::StartScrollbarAnimationOnImplThread,
                 impl_thread_weak_ptr_),
      delay);
}

void ThreadProxy::StartScrollbarAnimationOnImplThread() {
  impl().layer_tree_host_impl->StartScrollbarAnimation();
}

void ThreadProxy::DidActivatePendingTree() {
  TRACE_EVENT0("cc", "ThreadProxy::DidActivatePendingTreeOnImplThread");
  DCHECK(IsImplThread());
  DCHECK(!impl().layer_tree_host_impl->pending_tree());

  if (impl().completion_event_for_commit_held_on_tree_activation) {
    TRACE_EVENT_INSTANT0(
        "cc", "ReleaseCommitbyActivation", TRACE_EVENT_SCOPE_THREAD);
    DCHECK(impl().layer_tree_host_impl->settings().impl_side_painting);
    impl().completion_event_for_commit_held_on_tree_activation->Signal();
    impl().completion_event_for_commit_held_on_tree_activation = NULL;
  }

  UpdateBackgroundAnimateTicking();

  impl().timing_history.DidActivatePendingTree();
}

void ThreadProxy::DidManageTiles() {
  DCHECK(IsImplThread());
  impl().scheduler->DidManageTiles();
}

}  // namespace cc
/* [<][>][^][v][top][bottom][index][help] */
root/cc/trees/thread_proxy.cc

DEFINITIONS
