Update from https://crrev.com/307330

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 <set>
 #include <string>
@@ skipping 32 matching lines @@
 class PictureLayerImpl;
 class Proxy;
 class ResourceProvider;
 class TileManager;
 class UIResourceRequest;
 struct PendingPageScaleAnimation;
 struct RendererCapabilities;
 struct SelectionHandle;
 
 typedef std::list<UIResourceRequest> UIResourceRequestQueue;
+typedef SyncedProperty<AdditionGroup<gfx::Vector2dF>> SyncedElasticOverscroll;
 
 class CC_EXPORT LayerTreeImpl {
  public:
   static scoped_ptr<LayerTreeImpl> create(
       LayerTreeHostImpl* layer_tree_host_impl,
-      scoped_refptr<SyncedProperty<ScaleGroup>> page_scale_factor) {
-    return make_scoped_ptr(
-        new LayerTreeImpl(layer_tree_host_impl, page_scale_factor));
+      scoped_refptr<SyncedProperty<ScaleGroup>> page_scale_factor,
+      scoped_refptr<SyncedElasticOverscroll> elastic_overscroll) {
+    return make_scoped_ptr(new LayerTreeImpl(
+        layer_tree_host_impl, page_scale_factor, elastic_overscroll));
   }
   virtual ~LayerTreeImpl();
 
   void Shutdown();
   void ReleaseResources();
 
   // Methods called by the layer tree that pass-through or access LTHI.
   // ---------------------------------------------------------------------------
   const LayerTreeSettings& settings() const;
   const RendererCapabilitiesImpl& GetRendererCapabilities() const;
@@ skipping 101 matching lines @@
     return page_scale_factor()->Current(IsActiveTree());
   }
   float min_page_scale_factor() const { return min_page_scale_factor_; }
   float max_page_scale_factor() const { return max_page_scale_factor_; }
 
   float page_scale_delta() const { return page_scale_factor()->Delta(); }
 
   SyncedProperty<ScaleGroup>* page_scale_factor();
   const SyncedProperty<ScaleGroup>* page_scale_factor() const;
 
+  SyncedElasticOverscroll* elastic_overscroll() {
+    return elastic_overscroll_.get();
+  }
+  const SyncedElasticOverscroll* elastic_overscroll() const {
+    return elastic_overscroll_.get();
+  }
+
   // Updates draw properties and render surface layer list, as well as tile
   // priorities. Returns false if it was unable to update.
   bool UpdateDrawProperties();
 
   void set_needs_update_draw_properties() {
     needs_update_draw_properties_ = true;
   }
   bool needs_update_draw_properties() const {
     return needs_update_draw_properties_;
   }
@@ skipping 126 matching lines @@
     return top_controls_content_offset_ + top_controls_delta_;
   }
 
   void SetPendingPageScaleAnimation(
       scoped_ptr<PendingPageScaleAnimation> pending_animation);
   scoped_ptr<PendingPageScaleAnimation> TakePendingPageScaleAnimation();
 
  protected:
   explicit LayerTreeImpl(
       LayerTreeHostImpl* layer_tree_host_impl,
-      scoped_refptr<SyncedProperty<ScaleGroup>> page_scale_factor);
+      scoped_refptr<SyncedProperty<ScaleGroup>> page_scale_factor,
+      scoped_refptr<SyncedElasticOverscroll> elastic_overscroll);
   void ReleaseResourcesRecursive(LayerImpl* current);
   float ClampPageScaleFactorToLimits(float page_scale_factor) const;
   void PushPageScaleFactorAndLimits(const float* page_scale_factor,
                                     float min_page_scale_factor,
                                     float max_page_scale_factor);
   bool SetPageScaleFactorLimits(float min_page_scale_factor,
                                 float max_page_scale_factor);
   void DidUpdatePageScale();
 
   LayerTreeHostImpl* layer_tree_host_impl_;
@@ skipping 14 matching lines @@
   LayerImpl* inner_viewport_scroll_layer_;
   LayerImpl* outer_viewport_scroll_layer_;
 
   LayerSelectionBound selection_start_;
   LayerSelectionBound selection_end_;
 
   scoped_refptr<SyncedProperty<ScaleGroup>> page_scale_factor_;
   float min_page_scale_factor_;
   float max_page_scale_factor_;
 
+  scoped_refptr<SyncedElasticOverscroll> elastic_overscroll_;
+
   typedef base::hash_map<int, LayerImpl*> LayerIdMap;
   LayerIdMap layer_id_map_;
 
   std::vector<LayerImpl*> layers_with_copy_output_request_;
 
   // Persisted state for non-impl-side-painting.
   int scrolling_layer_id_from_previous_tree_;
 
   // List of visible layers for the most recently prepared frame.
   LayerImplList render_surface_layer_list_;
@@ skipping 30 matching lines @@
 
   scoped_ptr<PendingPageScaleAnimation> pending_page_scale_animation_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(LayerTreeImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_IMPL_H_