cc: Fix impl-side painting flashing due to missing tiles

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 80863512e12173bf4abed9bc536b7a7e66fe3915..008c0fbc318c94f4cf6ee01db4c8fa7ad27542fd 100644
--- a/cc/resources/picture_layer_tiling.h
+++ b/cc/resources/picture_layer_tiling.h
@@ -28,7 +28,7 @@ class PictureLayerTilingClient {
   // Create a tile at the given content_rect (in the contents scale of the
   // tiling) This might return null if the client cannot create such a tile.
   virtual scoped_refptr<Tile> CreateTile(
-    PictureLayerTiling* tiling,
+    const PictureLayerTiling* tiling,
     gfx::Rect content_rect) = 0;
   virtual void UpdatePile(Tile* tile) = 0;
   virtual gfx::Size CalculateTileSize(
@@ -156,6 +156,10 @@ class CC_EXPORT PictureLayerTiling {
       int64 target_area,
       gfx::Rect bounding_rect);
 
+  bool has_ever_been_updated() const {
+    return last_impl_frame_time_in_seconds_ != 0.0;
+  }
+
  protected:
   typedef std::pair<int, int> TileMapKey;
   typedef base::hash_map<TileMapKey, scoped_refptr<Tile> > TileMap;