Retry tree activation if raster tasks finish during first half of vsync interval

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/time.h"
@@ skipping 53 matching lines @@
       base::Time wall_clock_time) OVERRIDE;
   virtual bool ReduceContentsTextureMemoryOnImplThread(
       size_t limit_bytes,
       int priority_cutoff) OVERRIDE;
   virtual void ReduceWastedContentsTextureMemoryOnImplThread() OVERRIDE;
   virtual void SendManagedMemoryStats() OVERRIDE;
   virtual bool IsInsideDraw() OVERRIDE;
   virtual void RenewTreePriority() OVERRIDE {}
   virtual void RequestScrollbarAnimationOnImplThread(base::TimeDelta delay)
       OVERRIDE {}
+  virtual void DidFinishTileRasterTasks() OVERRIDE {}
 
   // Called by the legacy path where RenderWidget does the scheduling.
   void CompositeImmediately(base::TimeTicks frame_begin_time);
 
  private:
   explicit SingleThreadProxy(LayerTreeHost* layer_tree_host);
 
   bool CommitAndComposite(base::TimeTicks frame_begin_time,
                           gfx::Rect device_viewport_damage_rect,
                           LayerTreeHostImpl::FrameData* frame);
@@ skipping 86 matching lines @@
  private:
   DebugScopedSetImplThread impl_thread_;
   DebugScopedSetMainThreadBlocked main_thread_blocked_;
 
   DISALLOW_COPY_AND_ASSIGN(DebugScopedSetImplThreadAndMainThreadBlocked);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_SINGLE_THREAD_PROXY_H_