Implement on demand quad rasterization for PicturePiles.

cc/tile_draw_quad.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_TILE_DRAW_QUAD_H_
 #define CC_TILE_DRAW_QUAD_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "cc/cc_export.h"
 #include "cc/draw_quad.h"
@@ skipping 23 matching lines @@
               unsigned resource_id,
               const gfx::RectF& tex_coord_rect,
               gfx::Size texture_size,
               bool swizzle_contents);
 
   unsigned resource_id;
   gfx::RectF tex_coord_rect;
   gfx::Size texture_size;
   bool swizzle_contents;
 
+  virtual bool IsPictureQuad() const;
+
   virtual void IterateResources(const ResourceIteratorCallback& callback)
       OVERRIDE;
 
   static const TileDrawQuad* MaterialCast(const DrawQuad*);
- private:
+
+ protected:
+  virtual DrawQuad::Material material() const;
+
   TileDrawQuad();
 };
 
 }
 
 #endif  // CC_TILE_DRAW_QUAD_H_