cc: Disallow img.decode images from being checker imaged.

cc/tiles/tile_manager.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_TILES_TILE_MANAGER_H_
 #define CC_TILES_TILE_MANAGER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 225 matching lines @@
   // This method can only be used for debugging information, since it performs a
   // non trivial amount of work.
   std::unique_ptr<base::trace_event::ConvertableToTraceFormat>
   ActivationStateAsValue();
 
   void ActivationStateAsValueInto(base::trace_event::TracedValue* state);
   int num_of_tiles_with_checker_images() const {
     return num_of_tiles_with_checker_images_;
   }
 
+  CheckerImageTracker& checker_image_tracker() {
+    return checker_image_tracker_;
+  }
+
  protected:
   friend class Tile;
   // Must be called by tile during destruction.
   void Release(Tile* tile);
   Tile::Id GetUniqueTileId() { return ++next_tile_id_; }
 
  private:
   class MemoryUsage {
    public:
     MemoryUsage();
@@ skipping 148 matching lines @@
   base::WeakPtrFactory<TileManager> task_set_finished_weak_ptr_factory_;
   // The |ready_to_draw_callback_weak_ptr_factory_| is never invalidated.
   base::WeakPtrFactory<TileManager> ready_to_draw_callback_weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(TileManager);
 };
 
 }  // namespace cc
 
 #endif  // CC_TILES_TILE_MANAGER_H_