cc: Throttle tile priority updates to once a frame.

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 16 matching lines @@
   }
   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 updateTilePriorities() 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;
   virtual skia::RefPtr<SkPicture> getPicture() OVERRIDE;
 
   // PictureLayerTilingClient overrides.
@@ skipping 19 matching lines @@
   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);
 
   scoped_ptr<PictureLayerTilingSet> tilings_;
   scoped_refptr<PicturePileImpl> pile_;
   Region invalidation_;
 
+  int last_source_frame_number_;
+  int last_impl_frame_number_;
   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_