cc: Add some more infrastructure for two trees

cc/picture_layer_tiling_set.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_TILING_SET_H_
 #define CC_PICTURE_LAYER_TILING_SET_H_
 
 #include "cc/picture_layer_tiling.h"
 #include "cc/region.h"
 #include "cc/scoped_ptr_vector.h"
 #include "ui/gfx/size.h"
 
 namespace cc {
 
 class CC_EXPORT PictureLayerTilingSet {
  public:
   PictureLayerTilingSet(PictureLayerTilingClient* client);
   ~PictureLayerTilingSet();
 
   // Shallow copies all data (except client) from other.
-  void CloneFrom(const PictureLayerTilingSet& other);
+  void CloneAll(
+     const PictureLayerTilingSet& other,
+     const Region& invalidation);
+  void Clone(const PictureLayerTiling* tiling, const Region& invalidation);
+
+  // TODO(enne): Remove this once syncing happens to the pending tree.
+  void Invalidate(const Region& invalidation);
 
   void SetLayerBounds(gfx::Size layer_bounds);
   gfx::Size LayerBounds() const;
 
-  void Invalidate(const Region& invalidation);
-
-  void AddTiling(float contents_scale, gfx::Size tile_size);
+  const PictureLayerTiling* AddTiling(
+      float contents_scale,
+      gfx::Size tile_size);
   size_t num_tilings() const { return tilings_.size(); }
 
   void Reset();
 
   void UpdateTilePriorities(const gfx::Size& device_viewport,
                             float layer_content_scale_x,
                             float layer_content_scale_y,
                             const gfx::Transform& last_screen_transform,
                             const gfx::Transform& current_screen_transform,
                             double time_delta);
@@ skipping 30 matching lines @@
 
     Region current_region_;
     Region missing_region_;
     Region::Iterator region_iter_;
   };
 
  private:
   PictureLayerTilingClient* client_;
   gfx::Size layer_bounds_;
   ScopedPtrVector<PictureLayerTiling> tilings_;
+  Region invalidation_;
 
   friend class Iterator;
 };
 
 }  // namespace cc
 
 #endif  // CC_PICTURE_LAYER_TILING_SET_H_