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..e20e81436fe7085107f8fbf10aa1cb45d6c12b41 100644
--- a/cc/resources/picture_layer_tiling.h
+++ b/cc/resources/picture_layer_tiling.h
@@ -130,9 +130,9 @@ class CC_EXPORT PictureLayerTiling {
                                         const Region& layer_invalidation,
                                         const gfx::Size& new_layer_bounds);
   void CreateMissingTilesInLiveTilesRect();
-  void RemoveTilesInRegion(const Region& layer_region);
 
-  void SetClient(PictureLayerTilingClient* client);
+  void CreateSharedTilesFromPending(const PictureLayerTiling& other);
+
   void set_resolution(TileResolution resolution) { resolution_ = resolution; }
   TileResolution resolution() const { return resolution_; }
   void set_can_require_tiles_for_activation(bool can_require_tiles) {