Continue bitmap fetching for notifications.

chrome/common/chrome_notification_types.h

 // Copyright 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_COMMON_CHROME_NOTIFICATION_TYPES_H_
 #define CHROME_COMMON_CHROME_NOTIFICATION_TYPES_H_
 
 #include "build/build_config.h"
 #include "content/public/browser/notification_types.h"
 
@@ skipping 684 matching lines @@
   // Source<BalloonHost> with a pointer to the the balloon.  A
   // NOTIFY_BALLOON_DISCONNECTED is guaranteed before the source pointer
   // becomes junk. No details expected.
   NOTIFICATION_NOTIFY_BALLOON_CONNECTED,
 
   // This message is sent after a balloon is disconnected from the renderer
   // process. The source is a Source<BalloonHost> with a pointer to the
   // balloon host (the pointer is usable). No details are expected.
   NOTIFICATION_NOTIFY_BALLOON_DISCONNECTED,
 
+  // This notification is sent when an image is downloaded by a background
+  // process for the sake of notifications for an image.
+  NOTIFICATION_NOTIFY_BITMAP_FETCH_COMPLETE,

[dcheng, 2013/05/22 19:38:35]

Is it possible to make this change without adding a notification?

[Pete Williamson, 2013/05/23 16:47:29]

I will need to listen to this notification in the client code when I write it. 
I will definitely need some notification, let me know if you think it would be
wise to reuse an existing notification for this, but my suspicion is that would
be unwise.

[dcheng, 2013/05/23 19:32:25]

I would suggest using the delegate or observer pattern instead, like URLFetcher
does. As a whole, I believe we're trying our usage of notifications throughout
the code base where it makes sense.

+
   // Upgrade notifications ---------------------------------------------------
 
   // Sent when Chrome believes an update has been installed and available for
   // long enough with the user shutting down to let it take effect. See
   // upgrade_detector.cc for details on how long it waits. No details are
   // expected.
   NOTIFICATION_UPGRADE_RECOMMENDED,
 
   // Sent when a critical update has been installed. No details are expected.
   NOTIFICATION_CRITICAL_UPGRADE_INSTALLED,
@@ skipping 530 matching lines @@
   // Note:-
   // Currently only Content and Chrome define and use notifications.
   // Custom notifications not belonging to Content and Chrome should start
   // from here.
   NOTIFICATION_CHROME_END,
 };
 
 }  // namespace chrome
 
 #endif  // CHROME_COMMON_CHROME_NOTIFICATION_TYPES_H_