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

cc/trees/layer_tree_host_impl.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_LAYER_TREE_HOST_IMPL_H_
 #define CC_TREES_LAYER_TREE_HOST_IMPL_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 53 matching lines @@
       base::Time wall_clock_time) = 0;
   // Returns true if resources were deleted by this call.
   virtual bool ReduceContentsTextureMemoryOnImplThread(
       size_t limit_bytes,
       int priority_cutoff) = 0;
   virtual void ReduceWastedContentsTextureMemoryOnImplThread() = 0;
   virtual void SendManagedMemoryStats() = 0;
   virtual bool IsInsideDraw() = 0;
   virtual void RenewTreePriority() = 0;
   virtual void RequestScrollbarAnimationOnImplThread(base::TimeDelta delay) = 0;
+  virtual void DidFinishTileRasterTasks() = 0;
 
  protected:
   virtual ~LayerTreeHostImplClient() {}
 };
 
 // LayerTreeHostImpl owns the LayerImpl trees as well as associated rendering
 // state.
 class CC_EXPORT LayerTreeHostImpl : public InputHandlerClient,
                                     public RendererClient,
                                     public TileManagerClient,
@@ skipping 92 matching lines @@
   virtual void EnforceManagedMemoryPolicy(const ManagedMemoryPolicy& policy)
       OVERRIDE;
   virtual bool HasImplThread() const OVERRIDE;
   virtual bool ShouldClearRootRenderPass() const OVERRIDE;
   virtual CompositorFrameMetadata MakeCompositorFrameMetadata() const OVERRIDE;
   virtual bool AllowPartialSwap() const OVERRIDE;
 
   // TileManagerClient implementation.
   virtual void ScheduleManageTiles() OVERRIDE;
   virtual void DidInitializeVisibleTile() OVERRIDE;
+  virtual void DidFinishTileRasterTasks() OVERRIDE;
 
   // OutputSurfaceClient implementation.
   virtual void OnVSyncParametersChanged(base::TimeTicks timebase,
                                         base::TimeDelta interval) OVERRIDE;
   virtual void DidVSync(base::TimeTicks frame_time) OVERRIDE;
   virtual void OnSendFrameToParentCompositorAck(const CompositorFrameAck& ack)
       OVERRIDE;
 
   // Called from LayerTreeImpl.
   void OnCanDrawStateChangedForTree();
@@ skipping 273 matching lines @@
   scoped_ptr<AnimationRegistrar> animation_registrar_;
 
   RenderingStatsInstrumentation* rendering_stats_instrumentation_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHostImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_HOST_IMPL_H_