Allow partial update for notification update API

chrome/browser/notifications/notification.h

Index: chrome/browser/notifications/notification.h
diff --git a/chrome/browser/notifications/notification.h b/chrome/browser/notifications/notification.h
index 3e4685c7baaf03ae5d0f42121b28d2d175875e42..d0b69820b63e8e95e876077bf1e6ec6fe818762f 100644
--- a/chrome/browser/notifications/notification.h
+++ b/chrome/browser/notifications/notification.h
@@ -24,6 +24,8 @@
 // formated text and icon data.
 class Notification : public message_center::Notification {
  public:
+  Notification();

[dewittj, 2013/07/24 23:09:53]

I don't love this, since it creates an invalid notification.  Can we return a
pointer to the current Notification in the list from DoesIdExist and make a copy
of it in the calling code?  Or return a scoped_ptr<Notification> from
DoesIdExist that contains new Notification(currentNotification)?

[jianli, 2013/07/25 01:02:41]

Removed.

+
   // Initializes a notification with HTML content.
   Notification(const GURL& origin_url,
                const GURL& content_url,