Activate LayerImpl tree with sync+push instead of pointer swap

cc/picture_layer_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_PICTURE_LAYER_IMPL_H_
 #define CC_PICTURE_LAYER_IMPL_H_
 
 #include "cc/layer_impl.h"
 #include "cc/picture_layer_tiling.h"
 #include "cc/picture_layer_tiling_set.h"
@@ skipping 11 matching lines @@
                                    public PictureLayerTilingClient {
 public:
   static scoped_ptr<PictureLayerImpl> create(LayerTreeImpl* treeImpl, int id)
   {
       return make_scoped_ptr(new PictureLayerImpl(treeImpl, id));
   }
   virtual ~PictureLayerImpl();
 
   // LayerImpl overrides.
   virtual const char* layerTypeAsString() const OVERRIDE;
+  virtual scoped_ptr<LayerImpl> createLayerImpl(
+      LayerTreeImpl* treeImpl) OVERRIDE;
+  virtual void pushPropertiesTo(LayerImpl* layer) OVERRIDE;
   virtual void appendQuads(QuadSink&, AppendQuadsData&) OVERRIDE;
   virtual void dumpLayerProperties(std::string*, int indent) const OVERRIDE;
   virtual void didUpdateTransforms() OVERRIDE;
   virtual void didBecomeActive() OVERRIDE;
   virtual void didLoseOutputSurface() OVERRIDE;
   virtual void calculateContentsScale(
       float ideal_contents_scale,
       float* contents_scale_x,
       float* contents_scale_y,
       gfx::Size* content_bounds) OVERRIDE;
@@ skipping 14 matching lines @@
   virtual bool areVisibleResourcesReady() const OVERRIDE;
 
 protected:
   PictureLayerImpl(LayerTreeImpl* treeImpl, int id);
   PictureLayerTiling* AddTiling(float contents_scale);
   void SyncFromActiveLayer(const PictureLayerImpl* other);
   gfx::Size TileSize() const;
   void ManageTilings(float ideal_contents_scale);
   void CleanUpUnusedTilings(std::vector<PictureLayerTiling*> used_tilings);
 
-  PictureLayerTilingSet tilings_;
+  scoped_ptr<PictureLayerTilingSet> tilings_;
   scoped_refptr<PicturePileImpl> pile_;
   Region invalidation_;
 
   gfx::Transform last_screen_space_transform_;
   double last_update_time_;
   gfx::Size last_bounds_;
   gfx::Size last_content_bounds_;
   float last_content_scale_;
   float ideal_contents_scale_;
   bool is_mask_;
 
   friend class PictureLayer;
   DISALLOW_COPY_AND_ASSIGN(PictureLayerImpl);
 };
 
 }
 
 #endif  // CC_PICTURE_LAYER_IMPL_H_