Move overscroll bounce to impl thread

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 <list>
 #include <set>
 #include <string>
@@ skipping 39 matching lines @@
 class MemoryHistory;
 class PageScaleAnimation;
 class PaintTimeCounter;
 class PictureLayerImpl;
 class RasterTilePriorityQueue;
 class RasterWorkerPool;
 class RenderPassDrawQuad;
 class RenderingStatsInstrumentation;
 class ResourcePool;
 class ScrollbarLayerImplBase;
+class TreeScrollElasticityClient;
 class TextureMailboxDeleter;
 class TopControlsManager;
 class UIResourceBitmap;
 class UIResourceRequest;
 struct RendererCapabilitiesImpl;
 
 // LayerTreeHost->Proxy callback interface.
 class LayerTreeHostImplClient {
  public:
   virtual void UpdateRendererCapabilitiesOnImplThread() = 0;
@@ skipping 79 matching lines @@
   void PinchGestureBegin() override;
   void PinchGestureUpdate(float magnify_delta,
                           const gfx::Point& anchor) override;
   void PinchGestureEnd() override;
   void SetNeedsAnimate() override;
   bool IsCurrentlyScrollingLayerAt(const gfx::Point& viewport_point,
                                    InputHandler::ScrollInputType type) override;
   bool HaveTouchEventHandlersAt(const gfx::Point& viewport_port) override;
   scoped_ptr<SwapPromiseMonitor> CreateLatencyInfoSwapPromiseMonitor(
       ui::LatencyInfo* latency) override;
+  ScrollElasticityControllerClient*
+      GetScrollElasticityControllerClient() override;
 
   // TopControlsManagerClient implementation.
   void SetControlsTopOffset(float offset) override;
   float ControlsTopOffset() const override;
   void DidChangeTopControlsPosition() override;
   bool HaveRootScrollLayer() const override;
 
   struct CC_EXPORT FrameData : public RenderPassSink {
     FrameData();
     ~FrameData() override;
@@ skipping 451 matching lines @@
   scoped_ptr<LayerTreeImpl> recycle_tree_;
 
   InputHandlerClient* input_handler_client_;
   bool did_lock_scrolling_layer_;
   bool should_bubble_scrolls_;
   bool wheel_scrolling_;
   bool scroll_affects_scroll_handler_;
   int scroll_layer_id_when_mouse_over_scrollbar_;
   ScopedPtrVector<SwapPromise> swap_promises_for_main_thread_scroll_update_;
 
+  // The LayerTreeHostImpl class could implement the
+  // ScrollElasticityControllerClient interface itself, but an interface
+  // class is created to keep related state and functions separate.
+  scoped_ptr<TreeScrollElasticityClient> scroll_elasticity_client_;
+
   bool tile_priorities_dirty_;
 
   // The optional delegate for the root layer scroll offset.
   LayerScrollOffsetDelegate* root_layer_scroll_offset_delegate_;
   LayerTreeSettings settings_;
   LayerTreeDebugState debug_state_;
   bool visible_;
   ManagedMemoryPolicy cached_managed_memory_policy_;
 
   gfx::Vector2dF accumulated_root_overscroll_;
@@ skipping 77 matching lines @@
   std::vector<PictureLayerImpl::Pair> picture_layer_pairs_;
 
   bool requires_high_res_to_draw_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHostImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_HOST_IMPL_H_