cc: Don't swap PictureLayerTilingSet on activate.

cc/resources/picture_layer_tiling.h

Index: cc/resources/picture_layer_tiling.h
diff --git a/cc/resources/picture_layer_tiling.h b/cc/resources/picture_layer_tiling.h
index daa04851d9c22f8759e283d5fd0d9d048b3f22bb..c8b70be3c21a57e6aef6e0c9d266452b1dd35bed 100644
--- a/cc/resources/picture_layer_tiling.h
+++ b/cc/resources/picture_layer_tiling.h
@@ -121,18 +121,20 @@ class CC_EXPORT PictureLayerTiling {
   ~PictureLayerTiling();
 
   // Create a tiling with no tiles.  CreateTiles must be called to add some.
+  // TODO(danakj): Pass the raster_source here instead of the size, store the
+  // raster source instead of layer bounds?
   static scoped_ptr<PictureLayerTiling> Create(
       float contents_scale,
       const gfx::Size& layer_bounds,
       PictureLayerTilingClient* client);
   gfx::Size layer_bounds() const { return layer_bounds_; }
-  void UpdateTilesToCurrentRasterSource(RasterSource* raster_source,
-                                        const Region& layer_invalidation,
-                                        const gfx::Size& new_layer_bounds);
+  void Resize(const gfx::Size& new_layer_bounds);
+  void Invalidate(const Region& layer_invalidation);
+  void SetRasterSource(scoped_refptr<RasterSource> raster_source);
   void CreateMissingTilesInLiveTilesRect();
-  void RemoveTilesInRegion(const Region& layer_region);
 
-  void SetClient(PictureLayerTilingClient* client);
+  void CloneTilesAndPropertiesFrom(const PictureLayerTiling& twin_tiling);
+
   void set_resolution(TileResolution resolution) { resolution_ = resolution; }
   TileResolution resolution() const { return resolution_; }
   void set_can_require_tiles_for_activation(bool can_require_tiles) {
@@ -307,10 +309,13 @@ class CC_EXPORT PictureLayerTiling {
   const std::vector<Tile*>* GetEvictionTiles(TreePriority tree_priority,
                                              EvictionCategory category);
 
-  void Invalidate(const Region& layer_region);
-
-  void DoInvalidate(const Region& layer_region,
-                    bool recreate_invalidated_tiles);
+  // Save the required data for computing tile priorities later.
+  void UpdateTilePriorityRects(float content_to_screen_scale_,
+                               const gfx::Rect& visible_rect_in_content_space,
+                               const gfx::Rect& skewport,
+                               const gfx::Rect& soon_border_rect,
+                               const gfx::Rect& eventually_rect,
+                               const Occlusion& occlusion_in_layer_space);
 
   void UpdateTileAndTwinPriority(Tile* tile) const;
   void UpdateTilePriority(Tile* tile) const;
@@ -330,23 +335,23 @@ class CC_EXPORT PictureLayerTiling {
   double last_impl_frame_time_in_seconds_;
   gfx::Rect last_viewport_in_layer_space_;
   gfx::Rect last_visible_rect_in_content_space_;
-  float content_to_screen_scale_;
 
   bool can_require_tiles_for_activation_;
 
-  // Iteration rects in content space
+  // Iteration rects in content space.
   gfx::Rect current_visible_rect_;
   gfx::Rect current_skewport_rect_;
   gfx::Rect current_soon_border_rect_;
   gfx::Rect current_eventually_rect_;
+  // Other properties used for tile iteration and prioritization.
+  float current_content_to_screen_scale_;
+  Occlusion current_occlusion_in_layer_space_;
 
   bool has_visible_rect_tiles_;
   bool has_skewport_rect_tiles_;
   bool has_soon_border_rect_tiles_;
   bool has_eventually_rect_tiles_;
 
-  Occlusion current_occlusion_in_layer_space_;
-
   // TODO(reveman): Remove this in favour of an array of eviction_tiles_ when we
   // change all enums to have a consistent way of getting the count/last
   // element.