cc: Support animating scroll offset

cc/trees/layer_tree_impl.h

 // Copyright 2012 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_IMPL_H_
 #define CC_TREES_LAYER_TREE_IMPL_H_
 
 #include <list>
 #include <string>
 #include <vector>
@@ skipping 62 matching lines @@
   LayerImpl* FindActiveTreeLayerById(int id);
   LayerImpl* FindPendingTreeLayerById(int id);
   int MaxTextureSize() const;
   bool PinchGestureActive() const;
   base::TimeTicks CurrentFrameTimeTicks() const;
   base::Time CurrentFrameTime() const;
   base::TimeTicks CurrentPhysicalTimeTicks() const;
   void SetNeedsCommit();
   gfx::Size DrawViewportSize() const;
   void StartScrollbarAnimation();
+  void DidAnimateScrollOffset();
 
   // Tree specific methods exposed to layer-impl tree.
   // ---------------------------------------------------------------------------
   void SetNeedsRedraw();
 
   // TODO(nduca): These are implemented in cc files temporarily, but will become
   // trivial accessors in a followup patch.
   const LayerTreeDebugState& debug_state() const;
   float device_scale_factor() const;
   DebugRectHistory* debug_rect_history() const;
@@ skipping 180 matching lines @@
 
   UIResourceRequestQueue ui_resource_request_queue_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(LayerTreeImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_IMPL_H_