Update from https://crrev.com/305340

cc/trees/layer_tree_host.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_H_
 #define CC_TREES_LAYER_TREE_HOST_H_
 
 #include <limits>
 #include <list>
 #include <set>
@@ skipping 45 matching lines @@
 class LayerTreeHostSingleThreadClient;
 class PrioritizedResource;
 class PrioritizedResourceManager;
 class Region;
 class RenderingStatsInstrumentation;
 class ResourceProvider;
 class ResourceUpdateQueue;
 class SharedBitmapManager;
 class TopControlsManager;
 class UIResourceRequest;
+struct PendingPageScaleAnimation;
 struct RenderingStats;
 struct ScrollAndScaleSet;
 
 // Provides information on an Impl's rendering capabilities back to the
 // LayerTreeHost.
 struct CC_EXPORT RendererCapabilities {
   RendererCapabilities(ResourceFormat best_texture_format,
                        bool allow_partial_texture_updates,
                        int max_texture_size,
                        bool using_shared_memory_resources);
@@ skipping 96 matching lines @@
 
   void SetNextCommitWaitsForActivation();
 
   void SetNextCommitForcesRedraw();
 
   void SetAnimationEvents(scoped_ptr<AnimationEventsVector> events);
 
   void SetRootLayer(scoped_refptr<Layer> root_layer);
   Layer* root_layer() { return root_layer_.get(); }
   const Layer* root_layer() const { return root_layer_.get(); }
+  const Layer* overscroll_elasticity_layer() const {
+    return overscroll_elasticity_layer_.get();
+  }
   const Layer* page_scale_layer() const { return page_scale_layer_.get(); }
-  void RegisterViewportLayers(
-      scoped_refptr<Layer> page_scale_layer,
-      scoped_refptr<Layer> inner_viewport_scroll_layer,
-      scoped_refptr<Layer> outer_viewport_scroll_layer);
+  void RegisterViewportLayers(scoped_refptr<Layer> overscroll_elasticity_layer,
+                              scoped_refptr<Layer> page_scale_layer,
+                              scoped_refptr<Layer> inner_viewport_scroll_layer,
+                              scoped_refptr<Layer> outer_viewport_scroll_layer);
   Layer* inner_viewport_scroll_layer() const {
     return inner_viewport_scroll_layer_.get();
   }
   Layer* outer_viewport_scroll_layer() const {
     return outer_viewport_scroll_layer_.get();
   }
 
   void RegisterSelection(const LayerSelectionBound& start,
                          const LayerSelectionBound& end);
 
@@ skipping 110 matching lines @@
   // See swap_promise.h for how to use SwapPromise.
   void QueueSwapPromise(scoped_ptr<SwapPromise> swap_promise);
 
   void BreakSwapPromises(SwapPromise::DidNotSwapReason reason);
 
   size_t num_queued_swap_promises() const { return swap_promise_list_.size(); }
 
   void set_surface_id_namespace(uint32_t id_namespace);
   SurfaceSequence CreateSurfaceSequence();
 
+  void SetChildrenNeedBeginFrames(bool children_need_begin_frames) const;
+  void SendBeginFramesToChildren(const BeginFrameArgs& args) const;
+
  protected:
   LayerTreeHost(LayerTreeHostClient* client,
                 SharedBitmapManager* shared_bitmap_manager,
                 gpu::GpuMemoryBufferManager* gpu_memory_buffer_manager,
                 const LayerTreeSettings& settings);
   void InitializeThreaded(
       scoped_refptr<base::SingleThreadTaskRunner> main_task_runner,
       scoped_refptr<base::SingleThreadTaskRunner> impl_task_runner,
       scoped_ptr<BeginFrameSource> external_begin_frame_source);
   void InitializeSingleThreaded(
@@ skipping 99 matching lines @@
 
   // If set, this texture is used to fill in the parts of the screen not
   // covered by layers.
   scoped_ptr<ScopedUIResource> overhang_ui_resource_;
 
   typedef ScopedPtrVector<PrioritizedResource> TextureList;
   size_t partial_texture_update_requests_;
 
   scoped_ptr<AnimationRegistrar> animation_registrar_;
 
-  struct PendingPageScaleAnimation {
-    gfx::Vector2d target_offset;
-    bool use_anchor;
-    float scale;
-    base::TimeDelta duration;
-  };
   scoped_ptr<PendingPageScaleAnimation> pending_page_scale_animation_;
 
   bool in_paint_layer_contents_;
 
   static const int kTotalFramesToUseForLCDTextMetrics = 50;
   int total_frames_used_for_lcd_text_metrics_;
 
   struct LCDTextMetrics {
     LCDTextMetrics()
         : total_num_cc_layers(0),
           total_num_cc_layers_can_use_lcd_text(0),
           total_num_cc_layers_will_use_lcd_text(0) {}
 
     int64 total_num_cc_layers;
     int64 total_num_cc_layers_can_use_lcd_text;
     int64 total_num_cc_layers_will_use_lcd_text;
   };
   LCDTextMetrics lcd_text_metrics_;
   int id_;
   bool next_commit_forces_redraw_;
 
+  scoped_refptr<Layer> overscroll_elasticity_layer_;
   scoped_refptr<Layer> page_scale_layer_;
   scoped_refptr<Layer> inner_viewport_scroll_layer_;
   scoped_refptr<Layer> outer_viewport_scroll_layer_;
 
   LayerSelectionBound selection_start_;
   LayerSelectionBound selection_end_;
 
   SharedBitmapManager* shared_bitmap_manager_;
   gpu::GpuMemoryBufferManager* gpu_memory_buffer_manager_;
 
   ScopedPtrVector<SwapPromise> swap_promise_list_;
   std::set<SwapPromiseMonitor*> swap_promise_monitor_;
 
   uint32_t surface_id_namespace_;
   uint32_t next_surface_sequence_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHost);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_HOST_H_