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

chrome/browser/history/history_backend.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_HISTORY_BACKEND_H_
 #define CHROME_BROWSER_HISTORY_HISTORY_BACKEND_H_
 
 #include <set>
 #include <string>
 #include <utility>
@@ skipping 658 matching lines @@
       const std::vector<GURL>& icon_urls,
       int icon_types,
       int desired_size_in_dip,
       const std::vector<ui::ScaleFactor>& desired_scale_factors,
       FaviconResults* results);
 
   // Set the favicon bitmaps for |icon_id|.
   // For each entry in |favicon_bitmap_data|, if a favicon bitmap already
   // exists at the entry's pixel size, replace the favicon bitmap's data with
   // the entry's bitmap data. Otherwise add a new favicon bitmap.
+  // If not NULL, |favicon_bitmaps_changed| is set to whether any of the bitmap
+  // data at |icon_id| is changed as a result of calling this method.
   void SetFaviconBitmaps(
       FaviconID icon_id,
-      const std::vector<FaviconBitmapData>& favicon_bitmap_data);
+      const std::vector<FaviconBitmapData>& favicon_bitmap_data,
+      bool* favicon_bitmaps_changed);
 
   // Returns true if |favicon_bitmap_data| and |icon_url_sizes| passed to
   // SetFavicons() are valid.
   // Criteria:
   // 1) |icon_url_sizes| contains no more than
   //      kMaxFaviconsPerPage icon URLs.
   //      kMaxFaviconBitmapsPerIconURL favicon sizes for each icon URL.
   // 2) The icon URLs and favicon sizes of |favicon_bitmap_data| are a subset
   //    of |icon_url_sizes|.
   // 3) The favicon sizes for entries in |icon_url_sizes| which have associated
   //    data in |favicon_bitmap_data| is not history::GetDefaultFaviconSizes().
   // 4) FaviconBitmapData::bitmap_data contains non NULL bitmap data.
   bool ValidateSetFaviconsParams(
       const std::vector<FaviconBitmapData>& favicon_bitmap_data,
       const IconURLSizesMap& icon_url_sizes) const;
 
   // Sets the sizes that the thumbnail database knows that the favicon at
   // |icon_id| is available from the web. See history_types.h for a more
   // detailed description of FaviconSizes.
   // Deletes any favicon bitmaps currently mapped to |icon_id| whose pixel
   // sizes are not contained in |favicon_sizes|.
+  // |favicon_bitmaps_deleted| is set to true if at least one favicon bitmap
+  // is deleted.
   void SetFaviconSizes(FaviconID icon_id,
-                       const FaviconSizes& favicon_sizes);
+                       const FaviconSizes& favicon_sizes,
+                       bool* favicon_bitmaps_deleted);
+
+  // Returns true if |new_bitmap_data| equals the bitmap data at |bitmap_id|.
+  bool IsFaviconBitmapDataEqual(
+      FaviconBitmapID bitmap_id,
+      const scoped_refptr<base::RefCountedMemory>& new_bitmap_data);
 
   // Returns true if there are favicons for |page_url| and one of the types in
   // |icon_types|.
   // |favicon_bitmap_results| is set to the favicon bitmaps which most closely
   // match |desired_size_in_dip| and |desired_scale_factors|. If
   // |desired_size_in_dip| is 0, the largest favicon bitmap with one of the icon
   // types in |icon_types| is returned. If |icon_types| contains multiple icon
   // types and there are several matched icon types in the database, results
   // will only be returned for a single icon type in the priority of
   // TOUCH_PRECOMPOSED_ICON, TOUCH_ICON, and FAVICON. See the comment for
@@ skipping 186 matching lines @@
   // Used to provide the Android ContentProvider APIs.
   scoped_ptr<AndroidProviderBackend> android_provider_backend_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(HistoryBackend);
 };
 
 }  // namespace history
 
 #endif  // CHROME_BROWSER_HISTORY_HISTORY_BACKEND_H_