First fix to minimize copying of image data.

chrome/browser/dom_ui/dom_ui_thumbnail_source.h

 // Copyright (c) 2009 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 CHROME_BROWSER_DOM_UI_DOM_UI_THUMBNAIL_SOURCE_H_
 #define CHROME_BROWSER_DOM_UI_DOM_UI_THUMBNAIL_SOURCE_H_
 
 #include <string>
 #include <utility>
 #include <vector>
@@ skipping 35 matching lines @@
                        const NotificationDetails& details);
 
   // Fetch the specified resource.
   void DoDataRequest(const std::string& path, int request_id);
 
   Profile* profile_;
   CancelableRequestConsumerT<int, 0> cancelable_consumer_;
 
   // Raw PNG representation of the thumbnail to show when the thumbnail
   // database doesn't have a thumbnail for a webpage.
-  scoped_refptr<RefCountedBytes> default_thumbnail_;
+  scoped_refptr<RefCountedMemory> default_thumbnail_;
 
   // Store requests when the ThumbnailStore isn't ready. When a notification is
   // received that it is ready, then serve these requests.
   std::vector<std::pair<std::string, int> > pending_requests_;
 
   // To register to be notified when the ThumbnailStore is ready.
   NotificationRegistrar registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(DOMUIThumbnailSource);
 };
 
 #endif  // CHROME_BROWSER_DOM_UI_DOM_UI_THUMBNAIL_SOURCE_H_