Unify Android Webview and Chrome's fling

cc/trees/layer_tree_host_impl.h

Index: cc/trees/layer_tree_host_impl.h
diff --git a/cc/trees/layer_tree_host_impl.h b/cc/trees/layer_tree_host_impl.h
index ba5bb69e63061830e7f75c4104d3467780984458..2f4efd808477008390cb7504956250e876f3b9fd 100644
--- a/cc/trees/layer_tree_host_impl.h
+++ b/cc/trees/layer_tree_host_impl.h
@@ -179,7 +179,7 @@ class CC_EXPORT LayerTreeHostImpl
                                bool anchor_point,
                                float page_scale,
                                base::TimeDelta duration);
-  void SetNeedsAnimate() override;
+  void SetNeedsAnimateInput() override;
   bool IsCurrentlyScrollingLayerAt(const gfx::Point& viewport_point,
                                    InputHandler::ScrollInputType type) override;
   bool HaveWheelEventHandlersAt(const gfx::Point& viewport_point) override;
@@ -379,6 +379,7 @@ class CC_EXPORT LayerTreeHostImpl
   bool AnimationsAreVisible() { return visible() && CanDraw(); }
 
   void SetNeedsCommit() { client_->SetNeedsCommitOnImplThread(); }
+  void SetNeedsAnimate();
   void SetNeedsRedraw();
 
   ManagedMemoryPolicy ActualManagedMemoryPolicy() const;
@@ -581,6 +582,7 @@ class CC_EXPORT LayerTreeHostImpl
   // outer if the inner is at its scroll extents.
   void ScrollViewportInnerFirst(gfx::Vector2dF scroll_delta);
 
+  void AnimateInput(base::TimeTicks monotonic_time);
   void AnimatePageScale(base::TimeTicks monotonic_time);
   void AnimateScrollbars(base::TimeTicks monotonic_time);
   void AnimateTopControls(base::TimeTicks monotonic_time);
@@ -676,6 +678,8 @@ class CC_EXPORT LayerTreeHostImpl
 
   // The optional delegate for the root layer scroll offset.
   LayerScrollOffsetDelegate* root_layer_scroll_offset_delegate_;
+  LayerScrollOffsetDelegate::AnimationCallback root_layer_animation_callback_;
+
   const LayerTreeSettings settings_;
   LayerTreeDebugState debug_state_;
   bool visible_;