Add Observer in FaviconTabHelper

chrome/browser/favicon/favicon_handler.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_FAVICON_FAVICON_HANDLER_H_
 #define CHROME_BROWSER_FAVICON_FAVICON_HANDLER_H_
 
 #include <deque>
 #include <map>
 #include <vector>
@@ skipping 130 matching lines @@
       base::CancelableTaskTracker* tracker);
 
   virtual void SetHistoryFavicons(const GURL& page_url,
                                   const GURL& icon_url,
                                   favicon_base::IconType icon_type,
                                   const gfx::Image& image);
 
   // Returns true if the favicon should be saved.
   virtual bool ShouldSaveFavicon(const GURL& url);
 
-  // Notifies the driver that the favicon for the active entry was updated.
-  // |icon_url_changed| is true if a favicon with a different icon URL has been
-  // selected since the previous call to NotifyFaviconUpdated().
-  virtual void NotifyFaviconUpdated(bool icon_url_changed);
+  // Notifies the driver that the icon was updated and could be retreived

[sky, 2014/10/29 15:50:55]

retrieved

+  // from FaviconService, the favicon is also availabe from the active entry
+  // if download_largest_icon_ is not enabled for FAVICON type of icon.
+  // |icon_url| is current icon url and used to check whether a different icon
+  // URL has been selected since the previous call to NotifyFaviconUpdated().
+  virtual void NotifyFaviconUpdated(const GURL& icon_url);
 
  private:
   friend class TestFaviconHandler; // For testing
 
   // Represents an in progress download of an image from the renderer.
   struct DownloadRequest {
     DownloadRequest();
     ~DownloadRequest();
 
     DownloadRequest(const GURL& url,
@@ skipping 123 matching lines @@
 
   // This handler's driver.
   FaviconDriver* driver_;  // weak
 
   // Best image we've seen so far.  As images are downloaded from the page they
   // are stored here. When there is an exact match, or no more images are
   // available the favicon service and the current page are updated (assuming
   // the image is for a favicon).
   FaviconCandidate best_favicon_candidate_;
 
+  // The URL of TOUCH_ICON or TOUCH_PRCOMPOSED_ICON which has been used to
+  // notify the driver in the previous call of NotifyFaviconUpdated().
+  GURL notified_touch_icon_url_;
+
   DISALLOW_COPY_AND_ASSIGN(FaviconHandler);
 };
 
 #endif  // CHROME_BROWSER_FAVICON_FAVICON_HANDLER_H_