Don't request missing favicon on every page request.

chrome/browser/notifications/message_center_notification_manager.cc

 // 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.
 
 #include "chrome/browser/notifications/message_center_notification_manager.h"
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/prefs/pref_service.h"
 #include "chrome/browser/extensions/extension_info_map.h"
@@ skipping 361 matching lines @@
   if (optional_fields && optional_fields->HasKey(key)) {
     string16 url;
     optional_fields->GetString(key, &url);
     StartDownloadWithImage(notification, NULL, GURL(url), size, callback);
   }
 }
 
 void MessageCenterNotificationManager::ImageDownloads::DownloadComplete(
     const SetImageCallback& callback,
     int download_id,
+    int http_status_code,
     const GURL& image_url,
     int requested_size,
     const std::vector<SkBitmap>& bitmaps) {
   PendingDownloadCompleted();
 
   if (bitmaps.empty())
     return;
   gfx::Image image = gfx::Image::CreateFrom1xBitmap(bitmaps[0]);
   callback.Run(image);
 }
@@ skipping 87 matching lines @@
 
 MessageCenterNotificationManager::ProfileNotification*
     MessageCenterNotificationManager::FindProfileNotification(
         const std::string& id) const {
   NotificationMap::const_iterator iter = profile_notifications_.find(id);
   if (iter == profile_notifications_.end())
     return NULL;
 
   return (*iter).second;
 }