Update from https://crrev.com/305340

cc/trees/layer_tree_impl.h

Index: cc/trees/layer_tree_impl.h
diff --git a/cc/trees/layer_tree_impl.h b/cc/trees/layer_tree_impl.h
index 57e6ca129ca8a58ab4e3066f42619bcd3304f014..60a097d4c90799d2ca978c94ab7dc438de742946 100644
--- a/cc/trees/layer_tree_impl.h
+++ b/cc/trees/layer_tree_impl.h
@@ -44,6 +44,7 @@ class Proxy;
 class ResourceProvider;
 class TileManager;
 class UIResourceRequest;
+struct PendingPageScaleAnimation;
 struct RendererCapabilities;
 struct SelectionHandle;
 
@@ -137,10 +138,14 @@ class CC_EXPORT LayerTreeImpl {
   void SetCurrentlyScrollingLayer(LayerImpl* layer);
   void ClearCurrentlyScrollingLayer();
 
-  void SetViewportLayersFromIds(int page_scale_layer_id,
+  void SetViewportLayersFromIds(int overscroll_elasticity_layer,
+                                int page_scale_layer_id,
                                 int inner_viewport_scroll_layer_id,
                                 int outer_viewport_scroll_layer_id);
   void ClearViewportLayers();
+  LayerImpl* overscroll_elasticity_layer() {
+    return overscroll_elasticity_layer_;
+  }
   LayerImpl* page_scale_layer() { return page_scale_layer_; }
   void ApplySentScrollAndScaleDeltasFromAbortedCommit();
   void ApplyScrollDeltasSinceBeginMainFrame();
@@ -310,12 +315,9 @@ class CC_EXPORT LayerTreeImpl {
     return top_controls_content_offset_ + top_controls_delta_;
   }
 
-  void SetPageScaleAnimation(
-      const gfx::Vector2d& target_offset,
-      bool anchor_point,
-      float page_scale,
-      base::TimeDelta duration);
-  scoped_ptr<PageScaleAnimation> TakePageScaleAnimation();
+  void SetPendingPageScaleAnimation(
+      scoped_ptr<PendingPageScaleAnimation> pending_animation);
+  scoped_ptr<PendingPageScaleAnimation> TakePendingPageScaleAnimation();
 
  protected:
   explicit LayerTreeImpl(LayerTreeHostImpl* layer_tree_host_impl);
@@ -334,6 +336,7 @@ class CC_EXPORT LayerTreeImpl {
   SkColor background_color_;
   bool has_transparent_background_;
 
+  LayerImpl* overscroll_elasticity_layer_;
   LayerImpl* page_scale_layer_;
   LayerImpl* inner_viewport_scroll_layer_;
   LayerImpl* outer_viewport_scroll_layer_;
@@ -387,7 +390,7 @@ class CC_EXPORT LayerTreeImpl {
   float top_controls_delta_;
   float sent_top_controls_delta_;
 
-  scoped_ptr<PageScaleAnimation> page_scale_animation_;
+  scoped_ptr<PendingPageScaleAnimation> pending_page_scale_animation_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(LayerTreeImpl);