GTTF: Add missing virtual destructors.

cc/picture_layer_tiling.h

Index: cc/picture_layer_tiling.h
diff --git a/cc/picture_layer_tiling.h b/cc/picture_layer_tiling.h
index eafbba8228507bc30c80152e10e9900c096fb2ef..6f04e1faeac84831b6b26ea2af62b8c0a348bfec 100644
--- a/cc/picture_layer_tiling.h
+++ b/cc/picture_layer_tiling.h
@@ -21,13 +21,16 @@ namespace cc {
 class PictureLayerTiling;
 
 class PictureLayerTilingClient {
-  public:
-   // 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,
-     gfx::Rect content_rect) = 0;
-   virtual void UpdatePile(Tile* tile) = 0;
+ public:
+  // 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,
+      gfx::Rect content_rect) = 0;
+  virtual void UpdatePile(Tile* tile) = 0;
+
+ protected:
+  virtual ~PictureLayerTilingClient() { }
 };
 
 class CC_EXPORT PictureLayerTiling {