cc: Address comments for https://codereview.chromium.org/1287043002/

cc/trees/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/thread_proxy.h"
 
 #include <algorithm>
 #include <string>
 
 #include "base/auto_reset.h"
@@ skipping 201 matching lines @@
 
 void ThreadProxy::SetOutputSurface(scoped_ptr<OutputSurface> output_surface) {
   Proxy::ImplThreadTaskRunner()->PostTask(
       FROM_HERE,
       base::Bind(&ThreadProxy::InitializeOutputSurfaceOnImplThread,
                  impl_thread_weak_ptr_, base::Passed(&output_surface)));
 }
 
 scoped_ptr<OutputSurface> ThreadProxy::ReleaseOutputSurface() {
   DCHECK(IsMainThread());
+  DCHECK(layer_tree_host()->output_surface_lost());
+
   DebugScopedSetMainThreadBlocked main_thread_blocked(this);
   CompletionEvent completion;
   scoped_ptr<OutputSurface> output_surface;
   Proxy::ImplThreadTaskRunner()->PostTask(
       FROM_HERE,
       base::Bind(&ThreadProxy::ReleaseOutputSurfaceOnImplThread,
                  impl_thread_weak_ptr_, &completion, &output_surface));
   completion.Wait();
-  return output_surface.Pass();
+  return output_surface;
 }
 
 void ThreadProxy::DidInitializeOutputSurface(
     bool success,
     const RendererCapabilities& capabilities) {
   TRACE_EVENT0("cc", "ThreadProxy::DidInitializeOutputSurface");
   DCHECK(IsMainThread());
 
   if (!success) {
     layer_tree_host()->DidFailToInitializeOutputSurface();
@@ skipping 835 matching lines @@
                  success,
                  capabilities));
 
   if (success)
     impl().scheduler->DidCreateAndInitializeOutputSurface();
 }
 
 void ThreadProxy::ReleaseOutputSurfaceOnImplThread(
     CompletionEvent* completion,
     scoped_ptr<OutputSurface>* output_surface) {
-  TRACE_EVENT0("cc", "ThreadProxy::ReleaseOutputSurfaceOnImplThread");
   DCHECK(IsImplThread());
 
+  // Unlike DidLoseOutputSurfaceOnImplThread, we don't need to call
+  // LayerTreeHost::DidLoseOutputSurface since it already knows.
   impl().scheduler->DidLoseOutputSurface();
   *output_surface = impl().layer_tree_host_impl->ReleaseOutputSurface();
   completion->Signal();
 }
 
 void ThreadProxy::FinishGLOnImplThread(CompletionEvent* completion) {
   TRACE_EVENT0("cc", "ThreadProxy::FinishGLOnImplThread");
   DCHECK(IsImplThread());
   if (impl().layer_tree_host_impl->output_surface()) {
     ContextProvider* context_provider =
@@ skipping 164 matching lines @@
 
 void ThreadProxy::PostFrameTimingEvents(
     scoped_ptr<FrameTimingTracker::CompositeTimingSet> composite_events,
     scoped_ptr<FrameTimingTracker::MainFrameTimingSet> main_frame_events) {
   DCHECK(IsMainThread());
   layer_tree_host()->RecordFrameTimingEvents(composite_events.Pass(),
                                              main_frame_events.Pass());
 }
 
 }  // namespace cc