GTTF: Add missing virtual destructors.

cc/picture_layer_tiling.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_TILING_H_
 #define CC_PICTURE_LAYER_TILING_H_
 
 #include "base/basictypes.h"
 #include "base/hash_tables.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 13 matching lines @@
  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;
   virtual gfx::Size CalculateTileSize(
     gfx::Size current_tile_size,
     gfx::Size content_bounds) = 0;
+
+ protected:
+  virtual ~PictureLayerTilingClient() { }
 };
 
 class CC_EXPORT PictureLayerTiling {
  public:
   ~PictureLayerTiling();
 
   // Create a tiling with no tiles.  CreateTiles must be called to add some.
   static scoped_ptr<PictureLayerTiling> Create(float contents_scale);
   scoped_ptr<PictureLayerTiling> Clone() const;
 
@@ skipping 112 matching lines @@
   TileResolution resolution_;
   int last_source_frame_number_;
   double last_impl_frame_time_;
 
   friend class Iterator;
 };
 
 }  // namespace cc
 
 #endif  // CC_PICTURE_LAYER_TILING_H_