Avoid sending notifications when the bitmap data in history has not changed

chrome/browser/history/thumbnail_database.h

 // Copyright (c) 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 CHROME_BROWSER_HISTORY_THUMBNAIL_DATABASE_H_
 #define CHROME_BROWSER_HISTORY_THUMBNAIL_DATABASE_H_
 
 #include <vector>
 
 #include "base/gtest_prod_util.h"
@@ skipping 124 matching lines @@
       base::Time time,
       const gfx::Size& pixel_size);
 
   // Sets the bitmap data and the last updated time for the favicon bitmap at
   // |bitmap_id|.
   // Returns true if successful.
   bool SetFaviconBitmap(FaviconBitmapID bitmap_id,
                         scoped_refptr<base::RefCountedMemory> bitmap_data,
                         base::Time time);
 
+  // Sets the last updated time for the favicon bitmap at |bitmap_id|.
+  // Returns true if successful.
+  bool SetFaviconBitmapLastUpdateTime(FaviconBitmapID bitmap_id,
+                                      base::Time time);
+
   // Deletes the favicon bitmaps for the favicon with with |icon_id|.
   // Returns true if successful.
   bool DeleteFaviconBitmapsForFavicon(FaviconID icon_id);
 
   // Deletes the favicon bitmap with |bitmap_id|.
   // Returns true if successful.
   bool DeleteFaviconBitmap(FaviconBitmapID bitmap_id);
 
   // Favicons ------------------------------------------------------------------
 
@@ skipping 261 matching lines @@
   const HistoryPublisher* history_publisher_;
 
   // True if migration to TopSites has been done and the thumbnails
   // table should not be used.
   bool use_top_sites_;
 };
 
 }  // namespace history
 
 #endif  // CHROME_BROWSER_HISTORY_THUMBNAIL_DATABASE_H_