Make SingleThreadProxy a SchedulerClient

cc/trees/single_thread_proxy.cc

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/trees/single_thread_proxy.h"
 
 #include "base/auto_reset.h"
 #include "base/debug/trace_event.h"
 #include "cc/debug/benchmark_instrumentation.h"
 #include "cc/output/context_provider.h"
@@ skipping 15 matching lines @@
   return make_scoped_ptr(
       new SingleThreadProxy(layer_tree_host, client)).PassAs<Proxy>();
 }
 
 SingleThreadProxy::SingleThreadProxy(LayerTreeHost* layer_tree_host,
                                      LayerTreeHostSingleThreadClient* client)
     : Proxy(NULL),
       layer_tree_host_(layer_tree_host),
       client_(client),
       next_frame_is_newly_committed_frame_(false),
-      inside_draw_(false) {
+      inside_draw_(false),
+      defer_commits_(false),
+      finish_commit_deferred_(false),
+      weak_factory_(this) {
   TRACE_EVENT0("cc", "SingleThreadProxy::SingleThreadProxy");
   DCHECK(Proxy::IsMainThread());
   DCHECK(layer_tree_host);
 
   // Impl-side painting not supported without threaded compositing.
   CHECK(!layer_tree_host->settings().impl_side_painting)
       << "Threaded compositing must be enabled to use impl-side painting.";
 }
 
 void SingleThreadProxy::Start() {
   DebugScopedSetImplThread impl(this);
   layer_tree_host_impl_ = layer_tree_host_->CreateLayerTreeHostImpl(this);
+  SchedulerSettings scheduler_settings(layer_tree_host_->settings());
+  scheduler_on_impl_thread_ = Scheduler::Create(
+      this, scheduler_settings, layer_tree_host_->id(), MainThreadTaskRunner());
+  scheduler_on_impl_thread_->SetVisible(layer_tree_host_impl_->visible());
 }
 
 SingleThreadProxy::~SingleThreadProxy() {
   TRACE_EVENT0("cc", "SingleThreadProxy::~SingleThreadProxy");
   DCHECK(Proxy::IsMainThread());
   // Make sure Stop() got called or never Started.
   DCHECK(!layer_tree_host_impl_);
 }
 
 void SingleThreadProxy::FinishAllRendering() {
   TRACE_EVENT0("cc", "SingleThreadProxy::FinishAllRendering");
   DCHECK(Proxy::IsMainThread());
   {
     DebugScopedSetImplThread impl(this);
     layer_tree_host_impl_->FinishAllRendering();
   }
 }
 
 bool SingleThreadProxy::IsStarted() const {
   DCHECK(Proxy::IsMainThread());
   return layer_tree_host_impl_;
 }
 
 void SingleThreadProxy::SetLayerTreeHostClientReady() {
   TRACE_EVENT0("cc", "SingleThreadProxy::SetLayerTreeHostClientReady");
   // Scheduling is controlled by the embedder in the single thread case, so
   // nothing to do.
+  DCHECK(Proxy::IsMainThread());
+  DebugScopedSetImplThread impl(this);
+  scheduler_on_impl_thread_->SetCanStart();
 }
 
 void SingleThreadProxy::SetVisible(bool visible) {
   TRACE_EVENT0("cc", "SingleThreadProxy::SetVisible");
   DebugScopedSetImplThread impl(this);
   layer_tree_host_impl_->SetVisible(visible);
+  scheduler_on_impl_thread_->SetVisible(layer_tree_host_impl_->visible());

[danakj, 2014/06/13 18:34:10]

can this be the last thing in the method? scheduler kicks off new tasks so it's
kinda weird to do things after calling it (and has been a source of bugs)

[enne (OOO), 2014/06/13 20:10:42]

Done.

 
   // Changing visibility could change ShouldComposite().
   UpdateBackgroundAnimateTicking();
 }
 
 void SingleThreadProxy::CreateAndInitializeOutputSurface() {
   TRACE_EVENT0(
       "cc", "SingleThreadProxy::CreateAndInitializeOutputSurface");
   DCHECK(Proxy::IsMainThread());
   DCHECK(layer_tree_host_->output_surface_lost());
 
   scoped_ptr<OutputSurface> output_surface =
       layer_tree_host_->CreateOutputSurface();
 
   renderer_capabilities_for_main_thread_ = RendererCapabilities();
 
   bool success = !!output_surface;
   if (success) {
     DebugScopedSetMainThreadBlocked main_thread_blocked(this);
     DebugScopedSetImplThread impl(this);
     layer_tree_host_->DeleteContentsTexturesOnImplThread(
         layer_tree_host_impl_->resource_provider());
     success = layer_tree_host_impl_->InitializeRenderer(output_surface.Pass());
   }
 
   layer_tree_host_->OnCreateAndInitializeOutputSurfaceAttempted(success);
 
-  if (!success) {
-    // Force another recreation attempt to happen by requesting another commit.
-    SetNeedsCommit();
+  if (success) {
+    scheduler_on_impl_thread_->DidCreateAndInitializeOutputSurface();
+  } else {
+    Proxy::MainThreadTaskRunner()->PostTask(

[danakj, 2014/06/13 18:34:10]

Do you think posting vs just calling it inline here is better? Just want us to
think about it rather than copying it blindly.

[enne (OOO), 2014/06/13 20:10:41]

If it's not posted, then I need to do some extra scheduler logic to advance
frames, etc.  Otherwise it won't create the surface because it's already tried
to this frame.

+        FROM_HERE,
+        base::Bind(&SingleThreadProxy::CreateAndInitializeOutputSurface,
+                   weak_factory_.GetWeakPtr()));
   }
 }
 
 const RendererCapabilities& SingleThreadProxy::GetRendererCapabilities() const {
   DCHECK(Proxy::IsMainThread());
   DCHECK(!layer_tree_host_->output_surface_lost());
   return renderer_capabilities_for_main_thread_;
 }
 
 void SingleThreadProxy::SetNeedsAnimate() {
   TRACE_EVENT0("cc", "SingleThreadProxy::SetNeedsAnimate");
   DCHECK(Proxy::IsMainThread());
-  client_->ScheduleAnimation();
+  SetNeedsCommit();
 }
 
 void SingleThreadProxy::SetNeedsUpdateLayers() {
   TRACE_EVENT0("cc", "SingleThreadProxy::SetNeedsUpdateLayers");
   DCHECK(Proxy::IsMainThread());
-  client_->ScheduleComposite();
+  SetNeedsCommit();
 }
 
-void SingleThreadProxy::DoCommit(scoped_ptr<ResourceUpdateQueue> queue) {
+void SingleThreadProxy::DoCommit(base::TimeTicks frame_begin_time) {
   TRACE_EVENT0("cc", "SingleThreadProxy::DoCommit");
   DCHECK(Proxy::IsMainThread());
+  layer_tree_host_->WillBeginMainFrame();
+  layer_tree_host_->Layout();
+  layer_tree_host_->AnimateLayers(frame_begin_time);
+
+  if (PrioritizedResourceManager* contents_texture_manager =
+          layer_tree_host_->contents_texture_manager()) {
+    contents_texture_manager->UnlinkAndClearEvictedBackings();
+    contents_texture_manager->SetMaxMemoryLimitBytes(
+        layer_tree_host_impl_->memory_allocation_limit_bytes());
+    contents_texture_manager->SetExternalPriorityCutoff(
+        layer_tree_host_impl_->memory_allocation_priority_cutoff());
+  }
+
+  scoped_ptr<ResourceUpdateQueue> queue =
+      make_scoped_ptr(new ResourceUpdateQueue);
+
+  layer_tree_host_->UpdateLayers(queue.get());
+
+  layer_tree_host_->WillCommit();
+
   // Commit immediately.
   {
     DebugScopedSetMainThreadBlocked main_thread_blocked(this);
     DebugScopedSetImplThread impl(this);
 
     // This CapturePostTasks should be destroyed before CommitComplete() is
     // called since that goes out to the embedder, and we want the embedder
     // to receive its callbacks before that.
     BlockingTaskRunner::CapturePostTasks blocked;
 
@@ skipping 11 matching lines @@
             Proxy::MainThreadTaskRunner(),
             queue.Pass(),
             layer_tree_host_impl_->resource_provider());
     update_controller->Finalize();
 
     if (layer_tree_host_impl_->EvictedUIResourcesExist())
       layer_tree_host_->RecreateUIResources();
 
     layer_tree_host_->FinishCommitOnImplThread(layer_tree_host_impl_.get());
 
+    UpdateBackgroundAnimateTicking();
+
     layer_tree_host_impl_->CommitComplete();
 
 #if DCHECK_IS_ON
     // In the single-threaded case, the scale and scroll deltas should never be
     // touched on the impl layer tree.
     scoped_ptr<ScrollAndScaleSet> scroll_info =
         layer_tree_host_impl_->ProcessScrollDeltas();
     DCHECK(!scroll_info->scrolls.size());
     DCHECK_EQ(1.f, scroll_info->page_scale_delta);
 #endif
 
     RenderingStatsInstrumentation* stats_instrumentation =
         layer_tree_host_->rendering_stats_instrumentation();
     BenchmarkInstrumentation::IssueMainThreadRenderingStatsEvent(
         stats_instrumentation->main_thread_rendering_stats());
     stats_instrumentation->AccumulateAndClearMainThreadStats();
   }
   layer_tree_host_->CommitComplete();
+  layer_tree_host_->DidBeginMainFrame();
+  timing_history_.DidCommit();
+
   next_frame_is_newly_committed_frame_ = true;
 }
 
 void SingleThreadProxy::SetNeedsCommit() {
-  DCHECK(Proxy::IsMainThread());
-  client_->ScheduleComposite();
+  scheduler_on_impl_thread_->SetNeedsCommit();

[danakj, 2014/06/13 18:34:10]

DCHECK(IsMainThread) + DebugScopedImplThreadThing?

[enne (OOO), 2014/06/13 20:10:42]

Sure sure!

 }
 
 void SingleThreadProxy::SetNeedsRedraw(const gfx::Rect& damage_rect) {
   TRACE_EVENT0("cc", "SingleThreadProxy::SetNeedsRedraw");
+  DCHECK(Proxy::IsMainThread());
+  DebugScopedSetImplThread impl(this);
   SetNeedsRedrawRectOnImplThread(damage_rect);
-  client_->ScheduleComposite();
 }
 
 void SingleThreadProxy::SetNextCommitWaitsForActivation() {
   // There is no activation here other than commit. So do nothing.
+  DCHECK(Proxy::IsMainThread());
 }
 
 void SingleThreadProxy::SetDeferCommits(bool defer_commits) {
-  // Thread-only feature.
-  NOTREACHED();
+  DCHECK(Proxy::IsMainThread());
+  if (defer_commits_ == defer_commits)
+    return;
+
+  defer_commits_ = defer_commits;
+  if (!defer_commits_ && finish_commit_deferred_) {
+    scheduler_on_impl_thread_->NotifyBeginMainFrameStarted();
+    scheduler_on_impl_thread_->NotifyReadyToCommit();
+    finish_commit_deferred_ = false;
+  }
 }
 
-bool SingleThreadProxy::CommitRequested() const { return false; }
+bool SingleThreadProxy::CommitRequested() const {
+  DCHECK(Proxy::IsMainThread());
+  return finish_commit_deferred_;
+}
 
-bool SingleThreadProxy::BeginMainFrameRequested() const { return false; }
+bool SingleThreadProxy::BeginMainFrameRequested() const {
+  DCHECK(Proxy::IsMainThread());
+  return finish_commit_deferred_;
+}
 
 size_t SingleThreadProxy::MaxPartialTextureUpdates() const {
   return std::numeric_limits<size_t>::max();
 }
 
 void SingleThreadProxy::Stop() {
   TRACE_EVENT0("cc", "SingleThreadProxy::stop");
   DCHECK(Proxy::IsMainThread());
   {
     DebugScopedSetMainThreadBlocked main_thread_blocked(this);
     DebugScopedSetImplThread impl(this);
 
     BlockingTaskRunner::CapturePostTasks blocked;
     layer_tree_host_->DeleteContentsTexturesOnImplThread(
         layer_tree_host_impl_->resource_provider());
+    scheduler_on_impl_thread_.reset();
     layer_tree_host_impl_.reset();
   }
   layer_tree_host_ = NULL;
 }
 
 void SingleThreadProxy::OnCanDrawStateChanged(bool can_draw) {
   TRACE_EVENT1(
       "cc", "SingleThreadProxy::OnCanDrawStateChanged", "can_draw", can_draw);
   DCHECK(Proxy::IsImplThread());
   UpdateBackgroundAnimateTicking();
+  scheduler_on_impl_thread_->SetCanDraw(can_draw);
 }
 
 void SingleThreadProxy::NotifyReadyToActivate() {
-  // Thread-only feature.
+  // Impl-side painting only.
   NOTREACHED();
 }
 
 void SingleThreadProxy::SetNeedsRedrawOnImplThread() {
-  client_->ScheduleComposite();
+  scheduler_on_impl_thread_->SetNeedsRedraw();
 }
 
 void SingleThreadProxy::SetNeedsAnimateOnImplThread() {
   SetNeedsRedrawOnImplThread();
 }
 
 void SingleThreadProxy::SetNeedsManageTilesOnImplThread() {
-  // Thread-only/Impl-side-painting-only feature.
+  // Impl-side painting only.
   NOTREACHED();
 }
 
 void SingleThreadProxy::SetNeedsRedrawRectOnImplThread(
     const gfx::Rect& damage_rect) {
-  // TODO(brianderson): Once we move render_widget scheduling into this class,
-  // we can treat redraw requests more efficiently than CommitAndRedraw
-  // requests.
   layer_tree_host_impl_->SetViewportDamage(damage_rect);
-  SetNeedsCommit();
+  SetNeedsRedrawOnImplThread();
 }
 
 void SingleThreadProxy::DidInitializeVisibleTileOnImplThread() {
   // Impl-side painting only.
   NOTREACHED();
 }
 
 void SingleThreadProxy::SetNeedsCommitOnImplThread() {
-  client_->ScheduleComposite();
+  scheduler_on_impl_thread_->SetNeedsCommit();
 }
 
 void SingleThreadProxy::PostAnimationEventsToMainThreadOnImplThread(
     scoped_ptr<AnimationEventsVector> events) {
   TRACE_EVENT0(
       "cc", "SingleThreadProxy::PostAnimationEventsToMainThreadOnImplThread");
   DCHECK(Proxy::IsImplThread());
   DebugScopedSetMainThread main(this);
   layer_tree_host_->SetAnimationEvents(events.Pass());
 }
@@ skipping 31 matching lines @@
 }
 
 bool SingleThreadProxy::IsInsideDraw() { return inside_draw_; }
 
 void SingleThreadProxy::UpdateRendererCapabilitiesOnImplThread() {
   DCHECK(IsImplThread());
   renderer_capabilities_for_main_thread_ =
       layer_tree_host_impl_->GetRendererCapabilities().MainThreadCapabilities();
 }
 
+void SingleThreadProxy::DidActivatePendingTree() {
+  // Impl-side painting only.
+  NOTREACHED();
+}
+
+void SingleThreadProxy::DidManageTiles() {
+  // Impl-side painting only.
+  NOTREACHED();
+}
+
 void SingleThreadProxy::DidLoseOutputSurfaceOnImplThread() {
   TRACE_EVENT0("cc", "SingleThreadProxy::DidLoseOutputSurfaceOnImplThread");
-  // Cause a commit so we can notice the lost context.
-  SetNeedsCommitOnImplThread();
+  {
+    DebugScopedSetMainThread main(this);
+    // This must happen before we notify the scheduler as it may try to recreate
+    // the output surface if already in BEGIN_IMPL_FRAME_STATE_IDLE.
+    layer_tree_host_->DidLoseOutputSurface();
+  }
   client_->DidAbortSwapBuffers();
+  scheduler_on_impl_thread_->DidLoseOutputSurface();
 }
 
 void SingleThreadProxy::DidSwapBuffersOnImplThread() {
+  TRACE_EVENT0("cc", "SingleThreadProxy::DidSwapBuffersOnImplThread");
+  scheduler_on_impl_thread_->DidSwapBuffers();
   client_->DidPostSwapBuffers();
 }
 
 void SingleThreadProxy::DidSwapBuffersCompleteOnImplThread() {
   TRACE_EVENT0("cc", "SingleThreadProxy::DidSwapBuffersCompleteOnImplThread");
+  scheduler_on_impl_thread_->DidSwapBuffersComplete();
+  layer_tree_host_->DidCompleteSwapBuffers();
   client_->DidCompleteSwapBuffers();
 }
 
-// Called by the legacy scheduling path (e.g. where render_widget does the
-// scheduling)
+void SingleThreadProxy::BeginFrame(const BeginFrameArgs& args) {
+  TRACE_EVENT0("cc", "SingleThreadProxy::BeginFrame");
+  scheduler_on_impl_thread_->BeginImplFrame(args);
+}
+
 void SingleThreadProxy::CompositeImmediately(base::TimeTicks frame_begin_time) {
   TRACE_EVENT0("cc", "SingleThreadProxy::CompositeImmediately");
   DCHECK(Proxy::IsMainThread());
   DCHECK(!layer_tree_host_->output_surface_lost());
 
-  layer_tree_host_->AnimateLayers(frame_begin_time);
-
-  if (PrioritizedResourceManager* contents_texture_manager =
-          layer_tree_host_->contents_texture_manager()) {
-    contents_texture_manager->UnlinkAndClearEvictedBackings();
-    contents_texture_manager->SetMaxMemoryLimitBytes(
-        layer_tree_host_impl_->memory_allocation_limit_bytes());
-    contents_texture_manager->SetExternalPriorityCutoff(
-        layer_tree_host_impl_->memory_allocation_priority_cutoff());
-  }
-
-  scoped_ptr<ResourceUpdateQueue> queue =
-      make_scoped_ptr(new ResourceUpdateQueue);
-  layer_tree_host_->UpdateLayers(queue.get());
-  layer_tree_host_->WillCommit();
-  DoCommit(queue.Pass());
-  layer_tree_host_->DidBeginMainFrame();
+  DoCommit(frame_begin_time);
 
   LayerTreeHostImpl::FrameData frame;
-  if (DoComposite(frame_begin_time, &frame)) {
-    {
-      DebugScopedSetMainThreadBlocked main_thread_blocked(this);
-      DebugScopedSetImplThread impl(this);
-
-      // This CapturePostTasks should be destroyed before
-      // DidCommitAndDrawFrame() is called since that goes out to the embedder,
-      // and we want the embedder to receive its callbacks before that.
-      // NOTE: This maintains consistent ordering with the ThreadProxy since
-      // the DidCommitAndDrawFrame() must be post-tasked from the impl thread
-      // there as the main thread is not blocked, so any posted tasks inside
-      // the swap buffers will execute first.
-      BlockingTaskRunner::CapturePostTasks blocked;
-
-      layer_tree_host_impl_->SwapBuffers(frame);
-    }
-    DidSwapFrame();
-  }
+  DoComposite(frame_begin_time, &frame);
 }
 
 scoped_ptr<base::Value> SingleThreadProxy::AsValue() const {
   scoped_ptr<base::DictionaryValue> state(new base::DictionaryValue());
   {
     // The following line casts away const modifiers because it is just
     // setting debug state. We still want the AsValue() function and its
     // call chain to be const throughout.
     DebugScopedSetImplThread impl(const_cast<SingleThreadProxy*>(this));
 
@@ skipping 18 matching lines @@
   return layer_tree_host_impl_->visible() &&
          layer_tree_host_impl_->CanDraw();
 }
 
 void SingleThreadProxy::UpdateBackgroundAnimateTicking() {
   DCHECK(Proxy::IsImplThread());
   layer_tree_host_impl_->UpdateBackgroundAnimateTicking(
       !ShouldComposite() && layer_tree_host_impl_->active_tree()->root_layer());
 }
 
-bool SingleThreadProxy::DoComposite(
-    base::TimeTicks frame_begin_time,
-    LayerTreeHostImpl::FrameData* frame) {
+DrawResult SingleThreadProxy::DoComposite(base::TimeTicks frame_begin_time,
+                                          LayerTreeHostImpl::FrameData* frame) {
   TRACE_EVENT0("cc", "SingleThreadProxy::DoComposite");
   DCHECK(!layer_tree_host_->output_surface_lost());
 
-  bool lost_output_surface = false;
   {
     DebugScopedSetImplThread impl(this);
     base::AutoReset<bool> mark_inside(&inside_draw_, true);
 
     // We guard PrepareToDraw() with CanDraw() because it always returns a valid
     // frame, so can only be used when such a frame is possible. Since
     // DrawLayers() depends on the result of PrepareToDraw(), it is guarded on
     // CanDraw() as well.
     if (!ShouldComposite()) {
       UpdateBackgroundAnimateTicking();
-      return false;
+      return DrawResult::DRAW_ABORTED_CANT_DRAW;
     }
 
+    timing_history_.DidStartDrawing();
+
     layer_tree_host_impl_->Animate(
         layer_tree_host_impl_->CurrentFrameTimeTicks());
     UpdateBackgroundAnimateTicking();
 
     if (!layer_tree_host_impl_->IsContextLost()) {
       layer_tree_host_impl_->PrepareToDraw(frame);
       layer_tree_host_impl_->DrawLayers(frame, frame_begin_time);
       layer_tree_host_impl_->DidDrawAllLayers(*frame);
     }
-    lost_output_surface = layer_tree_host_impl_->IsContextLost();
 
     bool start_ready_animations = true;
     layer_tree_host_impl_->UpdateAnimationState(start_ready_animations);
 
     layer_tree_host_impl_->ResetCurrentFrameTimeForNextFrame();
+
+    timing_history_.DidFinishDrawing();
   }
 
-  if (lost_output_surface) {
-    layer_tree_host_->DidLoseOutputSurface();
-    return false;
+  {
+    DebugScopedSetImplThread impl(this);
+
+    if (layer_tree_host_impl_->IsContextLost()) {
+      DidLoseOutputSurfaceOnImplThread();
+    } else {
+      // This CapturePostTasks should be destroyed before
+      // DidCommitAndDrawFrame() is called since that goes out to the embedder,
+      // and we want the embedder to receive its callbacks before that.
+      // NOTE: This maintains consistent ordering with the ThreadProxy since
+      // the DidCommitAndDrawFrame() must be post-tasked from the impl thread
+      // there as the main thread is not blocked, so any posted tasks inside
+      // the swap buffers will execute first.
+      DebugScopedSetMainThreadBlocked main_thread_blocked(this);
+
+      BlockingTaskRunner::CapturePostTasks blocked;
+      layer_tree_host_impl_->SwapBuffers(*frame);
+    }
   }
+  DidCommitAndDrawFrame();
 
-  return true;
+  return DrawResult::DRAW_SUCCESS;
 }
 
-void SingleThreadProxy::DidSwapFrame() {
+void SingleThreadProxy::DidCommitAndDrawFrame() {
   if (next_frame_is_newly_committed_frame_) {
+    DebugScopedSetMainThread main(this);
     next_frame_is_newly_committed_frame_ = false;
     layer_tree_host_->DidCommitAndDrawFrame();
   }
 }
 
 bool SingleThreadProxy::CommitPendingForTesting() { return false; }
 
+scoped_ptr<base::Value> SingleThreadProxy::SchedulerAsValueForTesting() {
+  DebugScopedSetImplThread impl(this);
+  return scheduler_on_impl_thread_->AsValue().Pass();
+}
+
+void SingleThreadProxy::SetNeedsBeginFrame(bool enable) {
+  layer_tree_host_impl_->SetNeedsBeginFrame(enable);
+}
+
+void SingleThreadProxy::WillBeginImplFrame(const BeginFrameArgs& args) {
+  layer_tree_host_impl_->WillBeginImplFrame(args);
+}
+
+void SingleThreadProxy::ScheduledActionSendBeginMainFrame() {
+  TRACE_EVENT0("cc", "SingleThreadProxy::ScheduledActionSendBeginMainFrame");
+  if (defer_commits_) {
+    DCHECK(!finish_commit_deferred_);
+    finish_commit_deferred_ = true;
+    layer_tree_host_->DidDeferCommit();
+    return;

[danakj, 2014/06/13 18:34:10]

Hm! ThreadProxy saves the beginframe and runs it later when undeferred. Do you
think we can make it stop doing that since this doesn't?

[enne (OOO), 2014/06/13 20:10:42]

ThreadProxy's BeginMainFrameAndCommitState info comes from the compositor
thread.  So, it receives it and holds onto it until it decides to undefer that
commit.  SingleThreadProxy is all one one thread so it doesn't need to pass
along scroll deltas (since no compositor thread scrolling) or the current frame
time or the memory limits (which can just be applied immediately).

So, I think this makes this cleaner, but I don't see how to make ThreadProxy any
different.  They seem to have different needs.

+  }
+  timing_history_.DidBeginMainFrame();
+
+  scheduler_on_impl_thread_->NotifyBeginMainFrameStarted();
+  scheduler_on_impl_thread_->NotifyReadyToCommit();
+}
+
+DrawResult SingleThreadProxy::ScheduledActionDrawAndSwapIfPossible() {
+  DebugScopedSetImplThread impl(this);
+  if (layer_tree_host_impl_->IsContextLost()) {
+    DidCommitAndDrawFrame();

[danakj, 2014/06/13 18:34:10]

we did?

[enne (OOO), 2014/06/13 20:10:41]

So "context lost" is not a valid return from scheduled action draw.  ThreadProxy
also says DRAW_SUCCESS and DidCommitAndDrawFrame if the context is lost after
draw but before swap.  (It also doesn't check beforehand.)

Option 1 (this patch): a lost context is still a valid draw attempt and we'll
redraw after the context is restored so no use handling it specially.

Option 2: update scheduler to not explode when context lost is here but also
don't do anything different.  Update ThreadProxy to issue aborted draw return
values as well.  Update tests to not expect DidCommitAndDrawFrame (maybe they
need to wait for the single thread aborted swap callback?), although this adds
some weirded single thread vs threaded divergence.

+    return DrawResult::DRAW_SUCCESS;

[danakj, 2014/06/13 18:34:10]

why not DRAW_ABORTED_CONTEXT_LOST?

[enne (OOO), 2014/06/13 20:10:42]

See comment above.

+  }
+
+  LayerTreeHostImpl::FrameData frame;
+  return DoComposite(gfx::FrameTime::Now(), &frame);
+}
+
+DrawResult SingleThreadProxy::ScheduledActionDrawAndSwapForced() {
+  return ScheduledActionDrawAndSwapIfPossible();
+}
+
+void SingleThreadProxy::ScheduledActionCommit() {
+  DebugScopedSetMainThread main(this);
+  DoCommit(gfx::FrameTime::Now());
+}
+
+void SingleThreadProxy::ScheduledActionAnimate() {
+  TRACE_EVENT0("cc", "ScheduledActionAnimate");
+  layer_tree_host_impl_->Animate(
+      layer_tree_host_impl_->CurrentFrameTimeTicks());
+}
+
+void SingleThreadProxy::ScheduledActionUpdateVisibleTiles() {
+  // Impl-side painting only.
+  NOTREACHED();
+}
+
+void SingleThreadProxy::ScheduledActionActivatePendingTree() {
+  // Impl-side painting only.
+  NOTREACHED();
+}
+
+void SingleThreadProxy::ScheduledActionBeginOutputSurfaceCreation() {
+  DebugScopedSetMainThread main(this);
+  CreateAndInitializeOutputSurface();

[danakj, 2014/06/13 18:34:10]

If you make this a post-task does it save a lot of the hoop-dancing the patch
does to get around different call stacks?

[enne (OOO), 2014/06/13 20:10:42]

So a post task here to avoid a post task in CreateAndInitializeOutputSurface? 
What does that clean up?

[danakj, 2014/06/13 20:16:38]

I was thinking of the various "hold onto this pointer and clear it cuz it will
do the recreate synchronously type stuff that occurs with comments explaining it
in 2 or 3 places in this CL.

[enne (OOO), 2014/06/13 20:32:29]

Done in the last patch set.  There's an awkward comment block here now, but that
should bite fewer people than the synchronous output surface recreation, I
think.

+}
+
+void SingleThreadProxy::ScheduledActionManageTiles() {
+  // Impl-side painting only.
+  NOTREACHED();
+}
+
+void SingleThreadProxy::DidAnticipatedDrawTimeChange(base::TimeTicks time) {
+}
+
+base::TimeDelta SingleThreadProxy::DrawDurationEstimate() {
+  return timing_history_.DrawDurationEstimate();
+}
+
+base::TimeDelta SingleThreadProxy::BeginMainFrameToCommitDurationEstimate() {
+  return timing_history_.BeginMainFrameToCommitDurationEstimate();
+}
+
+base::TimeDelta SingleThreadProxy::CommitToActivateDurationEstimate() {
+  return timing_history_.CommitToActivateDurationEstimate();
+}
+
+void SingleThreadProxy::DidBeginImplFrameDeadline() {
+  layer_tree_host_impl_->ResetCurrentFrameTimeForNextFrame();
+}
+
 }  // namespace cc