cc: Split ThreadProxy into ProxyMain and ProxyImpl

cc/trees/proxy_impl.cc

+// Copyright 2015 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/proxy_impl.h"
+
+#include <algorithm>
+#include <string>
+
+#include "base/auto_reset.h"
+#include "base/bind.h"
+#include "base/trace_event/trace_event.h"
+#include "base/trace_event/trace_event_argument.h"
+#include "base/trace_event/trace_event_synthetic_delay.h"
+#include "cc/debug/benchmark_instrumentation.h"
+#include "cc/debug/devtools_instrumentation.h"
+#include "cc/input/input_handler.h"
+#include "cc/input/top_controls_manager.h"
+#include "cc/output/context_provider.h"
+#include "cc/output/output_surface.h"
+#include "cc/output/swap_promise.h"
+#include "cc/quads/draw_quad.h"
+#include "cc/scheduler/commit_earlyout_reason.h"
+#include "cc/scheduler/compositor_timing_history.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 "cc/trees/scoped_abort_remaining_swap_promises.h"
+#include "cc/trees/task_runner_provider.h"
+#include "gpu/command_buffer/client/gles2_interface.h"
+
+namespace cc {
+
+namespace {
+
+// Measured in seconds.
+const double kSmoothnessTakesPriorityExpirationDelay = 0.25;
+
+unsigned int nextBeginFrameId = 0;
+
+}  // namespace
+
+scoped_ptr<ProxyImpl> ProxyImpl::Create(
+    ChannelImpl* channel_impl,
+    LayerTreeHost* layer_tree_host,
+    TaskRunnerProvider* task_runner_provider,
+    scoped_ptr<BeginFrameSource> external_begin_frame_source) {
+  return make_scoped_ptr(new ProxyImpl(channel_impl, layer_tree_host,
+                                       task_runner_provider,
+                                       external_begin_frame_source.Pass()));
+}
+
+ProxyImpl::ProxyImpl(ChannelImpl* channel_impl,
+                     LayerTreeHost* layer_tree_host,
+                     TaskRunnerProvider* task_runner_provider,
+                     scoped_ptr<BeginFrameSource> external_begin_frame_source)
+    : layer_tree_host_id_(layer_tree_host->id()),
+      next_commit_waits_for_activation_(false),
+      commit_completion_event_(nullptr),
+      next_frame_is_newly_committed_frame_(false),
+      inside_draw_(false),
+      input_throttled_until_commit_(false),
+      task_runner_provider_(task_runner_provider),
+      smoothness_priority_expiration_notifier_(
+          task_runner_provider->ImplThreadTaskRunner(),
+          base::Bind(&ProxyImpl::RenewTreePriority, base::Unretained(this)),
+          base::TimeDelta::FromMilliseconds(
+              kSmoothnessTakesPriorityExpirationDelay * 1000)),
+      external_begin_frame_source_(external_begin_frame_source.Pass()),
+      rendering_stats_instrumentation_(
+          layer_tree_host->rendering_stats_instrumentation()),
+      channel_impl_(channel_impl) {
+  TRACE_EVENT0("cc", "ProxyImpl::ProxyImpl");
+  DCHECK(IsImplThread());
+  DCHECK(IsMainThreadBlocked());
+  DCHECK(layer_tree_host);
+
+  layer_tree_host_impl_ = layer_tree_host->CreateLayerTreeHostImpl(this);
+
+  SchedulerSettings scheduler_settings(
+      layer_tree_host->settings().ToSchedulerSettings());
+
+  scoped_ptr<CompositorTimingHistory> compositor_timing_history(
+      new CompositorTimingHistory(CompositorTimingHistory::RENDERER_UMA,
+                                  rendering_stats_instrumentation_));
+
+  scheduler_ = Scheduler::Create(this, scheduler_settings, layer_tree_host_id_,
+                                 task_runner_provider_->ImplThreadTaskRunner(),
+                                 external_begin_frame_source_.get(),
+                                 compositor_timing_history.Pass());
+
+  DCHECK_EQ(scheduler_->visible(), layer_tree_host_impl_->visible());
+}
+
+ProxyImpl::BlockedMainCommitOnly::BlockedMainCommitOnly()
+    : layer_tree_host(nullptr) {}
+
+ProxyImpl::BlockedMainCommitOnly::~BlockedMainCommitOnly() {}
+
+ProxyImpl::~ProxyImpl() {
+  TRACE_EVENT0("cc", "ProxyImpl::~ProxyImpl");
+  DCHECK(IsImplThread());
+  DCHECK(IsMainThreadBlocked());
+
+  scheduler_ = nullptr;
+  external_begin_frame_source_ = nullptr;
+  layer_tree_host_impl_ = nullptr;
+  // We need to explicitly shutdown the notifier to destroy any weakptrs it is
+  // holding while still on the compositor thread. This also ensures any
+  // callbacks holding a ProxyImpl pointer are cancelled.
+  smoothness_priority_expiration_notifier_.Shutdown();
+}
+
+void ProxyImpl::SetVisibleOnImpl(bool visible) {
+  TRACE_EVENT1("cc", "ProxyImpl::SetVisibleOnImplThread", "visible", visible);

[Wez, 2015/11/21 01:00:29]

Thread check here and function below?

[Khushal, 2015/11/23 20:07:19]

Done.

+  layer_tree_host_impl_->SetVisible(visible);
+  scheduler_->SetVisible(visible);
+}
+
+void ProxyImpl::SetThrottleFrameProductionOnImpl(bool throttle) {
+  TRACE_EVENT1("cc", "ProxyImpl::SetThrottleFrameProductionOnImplThread",
+               "throttle", throttle);
+  scheduler_->SetThrottleFrameProduction(throttle);
+}
+
+void ProxyImpl::SetNeedsCommitOnImpl() {
+  DCHECK(IsImplThread());
+  SetNeedsCommitOnImplThread();
+}
+
+void ProxyImpl::UpdateRendererCapabilitiesOnImplThread() {
+  DCHECK(IsImplThread());
+  channel_impl_->SetRendererCapabilitiesMainCopy(
+      layer_tree_host_impl_->GetRendererCapabilities()
+          .MainThreadCapabilities());
+}
+
+void ProxyImpl::DidLoseOutputSurfaceOnImplThread() {
+  TRACE_EVENT0("cc", "ProxyImpl::DidLoseOutputSurfaceOnImplThread");
+  DCHECK(IsImplThread());
+  channel_impl_->DidLoseOutputSurface();
+  scheduler_->DidLoseOutputSurface();
+}
+
+void ProxyImpl::CommitVSyncParameters(base::TimeTicks timebase,
+                                      base::TimeDelta interval) {
+  scheduler_->CommitVSyncParameters(timebase, interval);
+}
+
+void ProxyImpl::SetEstimatedParentDrawTime(base::TimeDelta draw_time) {
+  scheduler_->SetEstimatedParentDrawTime(draw_time);
+}
+
+void ProxyImpl::SetMaxSwapsPendingOnImplThread(int max) {
+  scheduler_->SetMaxSwapsPending(max);
+}
+
+void ProxyImpl::DidSwapBuffersOnImplThread() {
+  scheduler_->DidSwapBuffers();
+}
+
+void ProxyImpl::DidSwapBuffersCompleteOnImplThread() {
+  TRACE_EVENT0("cc,benchmark", "ProxyImpl::DidSwapBuffersCompleteOnImplThread");
+  DCHECK(IsImplThread());
+  scheduler_->DidSwapBuffersComplete();
+  channel_impl_->DidCompleteSwapBuffers();
+}
+
+void ProxyImpl::WillBeginImplFrame(const BeginFrameArgs& args) {
+  layer_tree_host_impl_->WillBeginImplFrame(args);
+  if (last_processed_begin_main_frame_args_.IsValid()) {
+    // Last processed begin main frame args records the frame args that we sent
+    // to the main thread for the last frame that we've processed. If that is
+    // set, that means the current frame is one past the frame in which we've
+    // finished the processing.
+    layer_tree_host_impl_->RecordMainFrameTiming(
+        last_processed_begin_main_frame_args_, args);
+    last_processed_begin_main_frame_args_ = BeginFrameArgs();
+  }
+}
+
+void ProxyImpl::OnResourcelessSoftareDrawStateChanged(bool resourceless_draw) {
+  DCHECK(IsImplThread());
+  scheduler_->SetResourcelessSoftareDraw(resourceless_draw);
+}
+
+void ProxyImpl::OnCanDrawStateChanged(bool can_draw) {
+  TRACE_EVENT1("cc", "ProxyImpl::OnCanDrawStateChanged", "can_draw", can_draw);
+  DCHECK(IsImplThread());
+  scheduler_->SetCanDraw(can_draw);
+}
+
+void ProxyImpl::NotifyReadyToActivate() {
+  TRACE_EVENT0("cc", "ProxyImpl::NotifyReadyToActivate");
+  scheduler_->NotifyReadyToActivate();
+}
+
+void ProxyImpl::NotifyReadyToDraw() {
+  TRACE_EVENT0("cc", "ProxyImpl::NotifyReadyToDraw");
+  scheduler_->NotifyReadyToDraw();
+}
+
+void ProxyImpl::SetNeedsCommitOnImplThread() {
+  TRACE_EVENT0("cc", "ProxyImpl::SetNeedsCommitOnImplThread");
+  DCHECK(IsImplThread());
+  scheduler_->SetNeedsBeginMainFrame();
+}
+
+void ProxyImpl::SetVideoNeedsBeginFrames(bool needs_begin_frames) {
+  TRACE_EVENT1("cc", "ProxyImpl::SetVideoNeedsBeginFrames",
+               "needs_begin_frames", needs_begin_frames);
+  DCHECK(IsImplThread());
+  // In tests the layer tree is destroyed after the scheduler is.
+  if (scheduler_)
+    scheduler_->SetVideoNeedsBeginFrames(needs_begin_frames);
+}
+
+void ProxyImpl::PostAnimationEventsToMainThreadOnImplThread(
+    scoped_ptr<AnimationEventsVector> events) {
+  TRACE_EVENT0("cc", "ProxyImpl::PostAnimationEventsToMainThreadOnImplThread");
+  DCHECK(IsImplThread());
+  channel_impl_->SetAnimationEvents(events.Pass());
+}
+
+bool ProxyImpl::IsInsideDraw() {
+  return inside_draw_;
+}
+
+void ProxyImpl::SetNeedsRedrawOnImpl(const gfx::Rect& damage_rect) {
+  DCHECK(IsImplThread());
+  SetNeedsRedrawRectOnImplThread(damage_rect);
+}
+
+void ProxyImpl::SetDeferCommitsOnImpl(bool defer_commits) const {
+  DCHECK(IsImplThread());
+  scheduler_->SetDeferCommits(defer_commits);
+}
+
+void ProxyImpl::SetNeedsRedrawOnImplThread() {
+  TRACE_EVENT0("cc", "ProxyImpl::SetNeedsRedrawOnImplThread");
+  DCHECK(IsImplThread());
+  scheduler_->SetNeedsRedraw();
+}
+
+void ProxyImpl::SetNeedsAnimateOnImplThread() {
+  TRACE_EVENT0("cc", "ProxyImpl::SetNeedsAnimateOnImplThread");
+  DCHECK(IsImplThread());
+  scheduler_->SetNeedsAnimate();
+}
+
+void ProxyImpl::SetNeedsPrepareTilesOnImplThread() {
+  DCHECK(IsImplThread());
+  scheduler_->SetNeedsPrepareTiles();
+}
+
+void ProxyImpl::SetNeedsRedrawRectOnImplThread(const gfx::Rect& damage_rect) {
+  DCHECK(IsImplThread());
+  layer_tree_host_impl_->SetViewportDamage(damage_rect);
+  SetNeedsRedrawOnImplThread();
+}
+
+void ProxyImpl::MainThreadHasStoppedFlingingOnImpl() {
+  DCHECK(IsImplThread());
+  layer_tree_host_impl_->MainThreadHasStoppedFlinging();
+}
+
+void ProxyImpl::SetInputThrottledUntilCommitOnImpl(bool is_throttled) {
+  DCHECK(IsImplThread());
+  if (is_throttled == input_throttled_until_commit_)
+    return;
+  input_throttled_until_commit_ = is_throttled;
+  RenewTreePriority();
+}
+
+ProxyImpl::BlockedMainCommitOnly& ProxyImpl::blocked_main_commit() {
+  DCHECK(IsMainThreadBlocked() && commit_completion_event_);
+  return main_thread_blocked_commit_vars_unsafe_;
+}
+
+void ProxyImpl::FinishAllRenderingOnImpl(CompletionEvent* completion) {
+  TRACE_EVENT0("cc", "ProxyImpl::FinishAllRenderingOnImplThread");
+  DCHECK(IsImplThread());
+  layer_tree_host_impl_->FinishAllRendering();
+  completion->Signal();
+}
+
+void ProxyImpl::ScheduledActionSendBeginMainFrame(const BeginFrameArgs& args) {

[Wez, 2015/11/21 01:00:29]

nit: Thread check?

[Khushal, 2015/11/23 20:07:19]

Done.

+  unsigned int begin_frame_id = nextBeginFrameId++;
+  benchmark_instrumentation::ScopedBeginFrameTask begin_frame_task(
+      benchmark_instrumentation::kSendBeginFrame, begin_frame_id);
+  scoped_ptr<BeginMainFrameAndCommitState> begin_main_frame_state(
+      new BeginMainFrameAndCommitState);
+  begin_main_frame_state->begin_frame_id = begin_frame_id;
+  begin_main_frame_state->begin_frame_args = args;
+  begin_main_frame_state->scroll_info =
+      layer_tree_host_impl_->ProcessScrollDeltas();
+  begin_main_frame_state->memory_allocation_limit_bytes =
+      layer_tree_host_impl_->memory_allocation_limit_bytes();
+  begin_main_frame_state->evicted_ui_resources =
+      layer_tree_host_impl_->EvictedUIResourcesExist();
+  // TODO(vmpstr): This needs to be fixed if
+  // main_frame_before_activation_enabled is set, since we might run this code
+  // twice before recording a duration. crbug.com/469824
+  last_begin_main_frame_args_ = begin_main_frame_state->begin_frame_args;
+  channel_impl_->BeginMainFrame(begin_main_frame_state.Pass());
+  devtools_instrumentation::DidRequestMainThreadFrame(layer_tree_host_id_);
+}
+
+void ProxyImpl::SendBeginMainFrameNotExpectedSoon() {
+  channel_impl_->BeginMainFrameNotExpectedSoon();

[Wez, 2015/11/21 01:00:29]

nit: Thread check?

The method definitions don't seem to match the declaration order from the
header, which makes them confusing to follow; can we order them to match, i.e.
group according to the interface they belong to?

[Khushal, 2015/11/23 20:07:19]

I have kept the order consistent with ThreadProxy. I think the functions were
ordered based on a logical call order for operations. For instance, in
ScheduledActionBeginMainFrame, we send BeginMainFrame to the main side and after
this we would expect either BeginMainFrameAbortedOnImpl or StartCommitOnImpl.
I'd rather the order stay as it was originally.

[Wez, 2015/11/24 22:36:59]

I get the desire not to create churn by fixing all the style violations here,
but in the case of method ordering and placement of variable declaration
(below), I don't see what the benefit is of keeping the existing violations,
given that (1) within this .cc file things would be consistent and (2) this code
file is not a copy/modification of ThreadProxy, at least as far as codereview is
concerned, so there doesn't seem to be benefit in terms of minimizing diffs.

[Khushal, 2015/11/25 06:48:11]

Fair enough. I have re-ordered both proxy_*.cc files to match the order in which
the functions are declared.

+}
+
+void ProxyImpl::StartCommitOnImpl(CompletionEvent* completion,
+                                  LayerTreeHost* layer_tree_host,
+                                  base::TimeTicks main_thread_start_time,
+                                  bool hold_commit_for_activation) {
+  TRACE_EVENT0("cc", "ProxyImpl::StartCommitOnImplThread");
+  DCHECK(!commit_completion_event_);
+  DCHECK(IsImplThread() && IsMainThreadBlocked());
+  DCHECK(scheduler_);
+  DCHECK(scheduler_->CommitPending());
+
+  if (hold_commit_for_activation) {
+    // This commit may be aborted. Store the value for
+    // hold_commit_for_activation so that whenever the next commit is started,
+    // the main thread will be unblocked only after pending tree activation.
+    next_commit_waits_for_activation_ = hold_commit_for_activation;
+  }
+
+  if (!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.

[Wez, 2015/11/21 01:00:29]

Not clear what this means; we're on the impl thread, right? What does it mean to
"inform to impl thread" that we're not already doing?

[Khushal, 2015/11/23 20:07:19]

I think this means that we should be doing a PostTask to tell the scheduler that
the main frame is started at the beginning of ProxyMain::BeginMainFrame but we
avoid the thread hop.
This has been kept consistent with ThreadProxy.

+  // But, we can avoid a PostTask in here.
+  scheduler_->NotifyBeginMainFrameStarted(main_thread_start_time);
+  commit_completion_event_ = completion;
+  DCHECK(!blocked_main_commit().layer_tree_host);
+  blocked_main_commit().layer_tree_host = layer_tree_host;
+  scheduler_->NotifyReadyToCommit();
+}
+
+void ProxyImpl::BeginMainFrameAbortedOnImpl(
+    CommitEarlyOutReason reason,
+    base::TimeTicks main_thread_start_time) {
+  TRACE_EVENT1("cc", "ProxyImpl::BeginMainFrameAbortedOnImplThread", "reason",
+               CommitEarlyOutReasonToString(reason));
+  DCHECK(IsImplThread());
+  DCHECK(scheduler_);
+  DCHECK(scheduler_->CommitPending());
+  DCHECK(!layer_tree_host_impl_->pending_tree());
+
+  if (CommitEarlyOutHandledCommit(reason)) {
+    SetInputThrottledUntilCommitOnImpl(false);
+    last_processed_begin_main_frame_args_ = last_begin_main_frame_args_;
+  }
+  layer_tree_host_impl_->BeginMainFrameAborted(reason);
+  scheduler_->NotifyBeginMainFrameStarted(main_thread_start_time);
+  scheduler_->BeginMainFrameAborted(reason);
+}
+
+void ProxyImpl::ScheduledActionAnimate() {
+  TRACE_EVENT0("cc", "ProxyImpl::ScheduledActionAnimate");
+  DCHECK(IsImplThread());
+
+  layer_tree_host_impl_->Animate();
+}
+
+void ProxyImpl::ScheduledActionCommit() {
+  TRACE_EVENT0("cc", "ProxyImpl::ScheduledActionCommit");
+  DCHECK(IsImplThread());
+  DCHECK(IsMainThreadBlocked());
+  DCHECK(commit_completion_event_);
+  DCHECK(blocked_main_commit().layer_tree_host);
+
+  layer_tree_host_impl_->BeginCommit();
+  blocked_main_commit().layer_tree_host->FinishCommitOnImplThread(
+      layer_tree_host_impl_.get());
+
+  // Remove the LayerTreeHost reference before the completion event is signaled
+  // and cleared. This is necessary since blocked_main_commit() allows access
+  // only while we have the completion event to ensure the main thread is
+  // blocked for a commit.
+  blocked_main_commit().layer_tree_host = nullptr;
+
+  if (next_commit_waits_for_activation_) {
+    // For some layer types in impl-side painting, the commit is held until
+    // the sync tree is activated.  It's also possible that the
+    // sync tree has already activated if there was no work to be done.
+    TRACE_EVENT_INSTANT0("cc", "HoldCommit", TRACE_EVENT_SCOPE_THREAD);
+  } else {
+    commit_completion_event_->Signal();
+    commit_completion_event_ = nullptr;
+  }
+
+  scheduler_->DidCommit();
+
+  // 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.
+  layer_tree_host_impl_->CommitComplete();
+
+  SetInputThrottledUntilCommitOnImpl(false);
+
+  next_frame_is_newly_committed_frame_ = true;
+}
+
+void ProxyImpl::ScheduledActionActivateSyncTree() {
+  TRACE_EVENT0("cc", "ProxyImpl::ScheduledActionActivateSyncTree");
+  DCHECK(IsImplThread());
+  layer_tree_host_impl_->ActivateSyncTree();
+}
+
+void ProxyImpl::ScheduledActionBeginOutputSurfaceCreation() {
+  TRACE_EVENT0("cc", "ProxyImpl::ScheduledActionBeginOutputSurfaceCreation");
+  DCHECK(IsImplThread());
+  channel_impl_->RequestNewOutputSurface();
+}
+
+DrawResult ProxyImpl::DrawSwapInternal(bool forced_draw) {
+  TRACE_EVENT_SYNTHETIC_DELAY("cc.DrawAndSwap");
+  DrawResult result;

[Wez, 2015/11/21 01:00:29]

Declare this immediately before its first use, i.e. before the if(CanDraw)
block.

[Khushal, 2015/11/23 20:07:19]

Keeping this consistent with ThreadProxy.

[Khushal, 2015/11/25 06:48:11]

Done.

+
+  DCHECK(IsImplThread());
+  DCHECK(layer_tree_host_impl_.get());
+
+  base::AutoReset<bool> mark_inside(&inside_draw_, true);
+
+  if (layer_tree_host_impl_->pending_tree()) {
+    bool update_lcd_text = false;
+    layer_tree_host_impl_->pending_tree()->UpdateDrawProperties(
+        update_lcd_text);
+  }
+
+  // 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.
+
+  LayerTreeHostImpl::FrameData frame;
+  bool draw_frame = false;
+
+  if (layer_tree_host_impl_->CanDraw()) {
+    result = layer_tree_host_impl_->PrepareToDraw(&frame);
+    draw_frame = forced_draw || result == DRAW_SUCCESS;

[Wez, 2015/11/21 01:00:29]

In the if(draw_frame) case below we always force result to DRAW_SUCCESS, so you
could get rid of draw_frame and instead have:

if (CanDraw()) {
  result = PrepareToDraw()
  if (forced_draw) result == DRAW_SUCCESS; // Ignore prepare failures if forced
to draw.

  if (result == DRAW_SUCCESS) {
    DrawLayers()
  }
} else {
  result = DRAW_ABORTED;
}

and the later draw_frame tests also become == DRAW_SUCCESS conditions.

[Khushal, 2015/11/23 20:07:19]

Keeping this consistent with ThreadProxy.

+  } else {
+    result = DRAW_ABORTED_CANT_DRAW;
+  }
+
+  if (draw_frame) {
+    layer_tree_host_impl_->DrawLayers(&frame);
+    result = DRAW_SUCCESS;
+  } else {
+    DCHECK_NE(DRAW_SUCCESS, result);
+  }
+  layer_tree_host_impl_->DidDrawAllLayers(frame);
+
+  bool start_ready_animations = draw_frame;
+  layer_tree_host_impl_->UpdateAnimationState(start_ready_animations);
+
+  if (draw_frame)
+    layer_tree_host_impl_->SwapBuffers(frame);
+
+  // Tell the main thread that the the newly-commited frame was drawn.
+  if (next_frame_is_newly_committed_frame_) {
+    next_frame_is_newly_committed_frame_ = false;
+    channel_impl_->DidCommitAndDrawFrame();
+  }
+
+  DCHECK_NE(INVALID_RESULT, result);
+  return result;
+}
+
+void ProxyImpl::ScheduledActionPrepareTiles() {
+  TRACE_EVENT0("cc", "ProxyImpl::ScheduledActionPrepareTiles");
+  layer_tree_host_impl_->PrepareTiles();
+}
+
+DrawResult ProxyImpl::ScheduledActionDrawAndSwapIfPossible() {
+  TRACE_EVENT0("cc", "ProxyImpl::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(layer_tree_host_impl_->CanDraw());
+
+  bool forced_draw = false;
+  return DrawSwapInternal(forced_draw);

[Wez, 2015/11/21 01:00:29]

nit: Presumably the variable is for clarity? Can we replace it with a static
enum to avoid the need for that?

[Khushal, 2015/11/23 20:07:19]

Keeping this consistent with ThreadProxy.

+}
+
+DrawResult ProxyImpl::ScheduledActionDrawAndSwapForced() {
+  TRACE_EVENT0("cc", "ProxyImpl::ScheduledActionDrawAndSwapForced");
+  bool forced_draw = true;
+  return DrawSwapInternal(forced_draw);
+}
+
+void ProxyImpl::ScheduledActionInvalidateOutputSurface() {
+  TRACE_EVENT0("cc", "ProxyImpl::ScheduledActionInvalidateOutputSurface");
+  DCHECK(layer_tree_host_impl_->output_surface());
+  layer_tree_host_impl_->output_surface()->Invalidate();
+}
+
+void ProxyImpl::DidFinishImplFrame() {
+  layer_tree_host_impl_->DidFinishImplFrame();

[Wez, 2015/11/21 01:00:29]

Thread check?

[Khushal, 2015/11/23 20:07:19]

Done.

+}
+
+void ProxyImpl::SendBeginFramesToChildren(const BeginFrameArgs& args) {
+  NOTREACHED() << "Only used by SingleProxyImpl";
+}
+
+void ProxyImpl::InitializeOutputSurfaceOnImpl(OutputSurface* output_surface) {
+  TRACE_EVENT0("cc", "ProxyImpl::InitializeOutputSurfaceOnImplThread");
+  DCHECK(IsImplThread());
+
+  LayerTreeHostImpl* host_impl = layer_tree_host_impl_.get();
+  bool success = host_impl->InitializeRenderer(output_surface);
+  RendererCapabilities capabilities;
+  if (success) {
+    capabilities =
+        host_impl->GetRendererCapabilities().MainThreadCapabilities();
+  }
+
+  channel_impl_->DidInitializeOutputSurface(success, capabilities);
+
+  if (success)
+    scheduler_->DidCreateAndInitializeOutputSurface();
+}
+
+void ProxyImpl::ReleaseOutputSurfaceOnImpl(CompletionEvent* completion) {
+  DCHECK(IsImplThread());
+
+  // Unlike DidLoseOutputSurfaceOnImplThread, we don't need to call
+  // LayerTreeHost::DidLoseOutputSurface since it already knows.
+  scheduler_->DidLoseOutputSurface();
+  layer_tree_host_impl_->ReleaseOutputSurface();
+  completion->Signal();
+}
+
+void ProxyImpl::FinishGLOnImpl(CompletionEvent* completion) {
+  TRACE_EVENT0("cc", "ProxyImpl::FinishGLOnImplThread");
+  DCHECK(IsImplThread());
+  if (layer_tree_host_impl_->output_surface()) {
+    ContextProvider* context_provider =
+        layer_tree_host_impl_->output_surface()->context_provider();
+    if (context_provider)
+      context_provider->ContextGL()->Finish();
+  }
+  completion->Signal();
+}
+
+void ProxyImpl::MainFrameWillHappenOnImplForTesting(
+    CompletionEvent* completion,
+    bool* main_frame_will_happen) {
+  DCHECK(IsImplThread());
+  if (layer_tree_host_impl_->output_surface()) {
+    *main_frame_will_happen = scheduler_->MainFrameForTestingWillHappen();
+  } else {
+    *main_frame_will_happen = false;
+  }
+  completion->Signal();
+}
+
+void ProxyImpl::RenewTreePriority() {
+  DCHECK(IsImplThread());
+  bool smoothness_takes_priority =
+      layer_tree_host_impl_->pinch_gesture_active() ||
+      layer_tree_host_impl_->page_scale_animation_active() ||
+      layer_tree_host_impl_->IsActivelyScrolling();
+
+  // Schedule expiration if smoothness currently takes priority.
+  if (smoothness_takes_priority)
+    smoothness_priority_expiration_notifier_.Schedule();
+
+  // We use the same priority for both trees by default.
+  TreePriority priority = SAME_PRIORITY_FOR_BOTH_TREES;
+
+  // Smoothness takes priority if we have an expiration for it scheduled.
+  if (smoothness_priority_expiration_notifier_.HasPendingNotification())
+    priority = SMOOTHNESS_TAKES_PRIORITY;
+
+  // New content always takes priority when there is an invalid viewport size or
+  // ui resources have been evicted.
+  if (layer_tree_host_impl_->active_tree()->ViewportSizeInvalid() ||
+      layer_tree_host_impl_->EvictedUIResourcesExist() ||
+      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.
+    layer_tree_host_impl_->SetRequiresHighResToDraw();
+    priority = NEW_CONTENT_TAKES_PRIORITY;
+  }
+
+  layer_tree_host_impl_->SetTreePriority(priority);
+
+  // Only put the scheduler in impl latency prioritization mode if we don't
+  // have a scroll listener. This gives the scroll listener a better chance of
+  // handling scroll updates within the same frame. The tree itself is still
+  // kept in prefer smoothness mode to allow checkerboarding.
+  scheduler_->SetImplLatencyTakesPriority(
+      priority == SMOOTHNESS_TAKES_PRIORITY &&
+      !layer_tree_host_impl_->scroll_affects_scroll_handler());
+
+  // 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 (layer_tree_host_impl_->output_surface()) {
+    layer_tree_host_impl_->output_surface()->UpdateSmoothnessTakesPriority(
+        priority == SMOOTHNESS_TAKES_PRIORITY);
+  }
+}
+
+void ProxyImpl::PostDelayedAnimationTaskOnImplThread(const base::Closure& task,
+                                                     base::TimeDelta delay) {
+  task_runner_provider_->ImplThreadTaskRunner()->PostDelayedTask(FROM_HERE,
+                                                                 task, delay);
+}
+
+void ProxyImpl::DidActivateSyncTree() {
+  TRACE_EVENT0("cc", "ProxyImpl::DidActivateSyncTreeOnImplThread");
+  DCHECK(IsImplThread());
+
+  if (next_commit_waits_for_activation_) {
+    TRACE_EVENT_INSTANT0("cc", "ReleaseCommitbyActivation",
+                         TRACE_EVENT_SCOPE_THREAD);
+    DCHECK(commit_completion_event_);
+    commit_completion_event_->Signal();
+    commit_completion_event_ = nullptr;
+    next_commit_waits_for_activation_ = false;
+  }
+
+  last_processed_begin_main_frame_args_ = last_begin_main_frame_args_;
+}
+
+void ProxyImpl::WillPrepareTiles() {
+  DCHECK(IsImplThread());
+  scheduler_->WillPrepareTiles();
+}
+
+void ProxyImpl::DidPrepareTiles() {
+  DCHECK(IsImplThread());
+  scheduler_->DidPrepareTiles();
+}
+
+void ProxyImpl::DidCompletePageScaleAnimationOnImplThread() {
+  DCHECK(IsImplThread());
+  channel_impl_->DidCompletePageScaleAnimation();
+}
+
+void ProxyImpl::OnDrawForOutputSurface() {
+  DCHECK(IsImplThread());
+  scheduler_->OnDrawForOutputSurface();
+}
+
+void ProxyImpl::UpdateTopControlsStateOnImpl(TopControlsState constraints,
+                                             TopControlsState current,
+                                             bool animate) {
+  DCHECK(IsImplThread());
+  layer_tree_host_impl_->top_controls_manager()->UpdateTopControlsState(
+      constraints, current, animate);
+}
+
+void ProxyImpl::PostFrameTimingEventsOnImplThread(
+    scoped_ptr<FrameTimingTracker::CompositeTimingSet> composite_events,
+    scoped_ptr<FrameTimingTracker::MainFrameTimingSet> main_frame_events) {
+  DCHECK(IsImplThread());
+  channel_impl_->PostFrameTimingEventsOnMain(composite_events.Pass(),
+                                             main_frame_events.Pass());
+}
+
+bool ProxyImpl::IsImplThread() const {
+  return task_runner_provider_->IsImplThread();
+}
+
+bool ProxyImpl::IsMainThreadBlocked() const {
+  return task_runner_provider_->IsMainThreadBlocked();
+}
+
+bool ProxyImpl::HasCommitCompletionEvent() const {
+  return !!commit_completion_event_;

[Wez, 2015/11/21 01:00:29]

nit: Prefer foo != nullptr rather than !!foo

[Khushal, 2015/11/23 20:07:19]

Done.

+}
+
+}  // namespace cc