cc: Measure compositor timing with finer granularity

cc/trees/single_thread_proxy.h

 // 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.
 
 #ifndef CC_TREES_SINGLE_THREAD_PROXY_H_
 #define CC_TREES_SINGLE_THREAD_PROXY_H_
 
 #include <limits>
 
 #include "base/cancelable_callback.h"
@@ skipping 83 matching lines @@
   void SetNeedsPrepareTilesOnImplThread() override;
   void SetNeedsCommitOnImplThread() override;
   void SetVideoNeedsBeginFrames(bool needs_begin_frames) override;
   void PostAnimationEventsToMainThreadOnImplThread(
       scoped_ptr<AnimationEventsVector> events) override;
   bool IsInsideDraw() override;
   void RenewTreePriority() override {}
   void PostDelayedAnimationTaskOnImplThread(const base::Closure& task,
                                             base::TimeDelta delay) override {}
   void DidActivateSyncTree() override;
+  void WillPrepareTiles() override;
   void DidPrepareTiles() override;
   void DidCompletePageScaleAnimationOnImplThread() override;
   void OnDrawForOutputSurface() override;
   void PostFrameTimingEventsOnImplThread(
       scoped_ptr<FrameTimingTracker::CompositeTimingSet> composite_events,
       scoped_ptr<FrameTimingTracker::MainFrameTimingSet> main_frame_events)
       override;
 
   void SetDebugState(const LayerTreeDebugState& debug_state) override {}
 
@@ skipping 118 matching lines @@
  private:
   DebugScopedSetImplThread impl_thread_;
   DebugScopedSetMainThreadBlocked main_thread_blocked_;
 
   DISALLOW_COPY_AND_ASSIGN(DebugScopedSetImplThreadAndMainThreadBlocked);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_SINGLE_THREAD_PROXY_H_