cc: Add image decode control in the compositor.

cc/playback/display_item_list.h

 // Copyright 2014 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_PLAYBACK_DISPLAY_ITEM_LIST_H_
 #define CC_PLAYBACK_DISPLAY_ITEM_LIST_H_
 
 #include "base/gtest_prod_util.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 77 matching lines @@
 
   scoped_refptr<base::trace_event::ConvertableToTraceFormat> AsValue(
       bool include_items) const;
 
   void EmitTraceSnapshot() const;
 
   void GenerateDiscardableImagesMetadata();
   void GetDiscardableImagesInRect(const gfx::Rect& rect,
                                   float raster_scale,
                                   std::vector<DrawImage>* images);
+  bool MayHaveDiscardableImages() const;
 
   gfx::Rect VisualRectForTesting(int index) { return visual_rects_[index]; }
 
  private:
   DisplayItemList(gfx::Rect layer_rect,
                   const DisplayItemListSettings& display_list_settings,
                   bool retain_individual_display_items);
   ~DisplayItemList();
 
   // While appending new items, if they are not being retained, this can process
@@ skipping 34 matching lines @@
   DiscardableImageMap image_map_;
 
   friend class base::RefCountedThreadSafe<DisplayItemList>;
   FRIEND_TEST_ALL_PREFIXES(DisplayItemListTest, ApproximateMemoryUsage);
   DISALLOW_COPY_AND_ASSIGN(DisplayItemList);
 };
 
 }  // namespace cc
 
 #endif  // CC_PLAYBACK_DISPLAY_ITEM_LIST_H_