Update from chromium https://crrev.com/304586

cc/surfaces/surface_aggregator.h

 // Copyright 2014 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_SURFACES_SURFACE_AGGREGATOR_H_
 #define CC_SURFACES_SURFACE_AGGREGATOR_H_
 
 #include <set>
 
 #include "base/containers/hash_tables.h"
@@ skipping 34 matching lines @@
   void CopySharedQuadState(const SharedQuadState* source_sqs,
                            const gfx::Transform& content_to_target_transform,
                            RenderPass* dest_render_pass);
   void CopyQuadsToPass(const QuadList& source_quad_list,
                        const SharedQuadStateList& source_shared_quad_state_list,
                        const gfx::Transform& content_to_target_transform,
                        RenderPass* dest_pass,
                        SurfaceId surface_id);
   void CopyPasses(const DelegatedFrameData* frame_data, Surface* surface);
 
+  // Remove Surfaces that were referenced before but aren't currently
+  // referenced from the ResourceProvider.
+  void RemoveUnreferencedChildren();
+
   bool TakeResources(Surface* surface,
                      const DelegatedFrameData* frame_data,
                      RenderPassList* render_pass_list);
   int ChildIdForSurface(Surface* surface);
   gfx::Rect DamageRectForSurface(const Surface* surface,
                                  const RenderPass& source);
 
   SurfaceManager* manager_;
   ResourceProvider* provider_;
 
@@ skipping 25 matching lines @@
 
   // Resource list for the aggregated frame.
   TransferableResourceArray* dest_resource_list_;
 
   DISALLOW_COPY_AND_ASSIGN(SurfaceAggregator);
 };
 
 }  // namespace cc
 
 #endif  // CC_SURFACES_SURFACE_AGGREGATOR_H_