[Mac][MC] Implement notification updates and relayouts.

ui/message_center/cocoa/notification_controller.h

 // Copyright (c) 2013 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 UI_MESSAGE_CENTER_COCOA_NOTIFICATION_CONTROLLER_H_
 #define UI_MESSAGE_CENTER_COCOA_NOTIFICATION_CONTROLLER_H_
 
 #import <Cocoa/Cocoa.h>
 
 #include <string>
@@ skipping 33 matching lines @@
   scoped_nsobject<NSTextField> title_;
 
   // Body text of the message.
   scoped_nsobject<NSTextField> message_;
 }
 
 // Creates a new controller for a given notification.
 - (id)initWithNotification:(const message_center::Notification*)notification
     messageCenter:(message_center::MessageCenter*)messageCenter;
 
+// If the model object changes, this method will update the views to reflect
+// the new model object. Returns the updated frame of the notification.
+- (NSRect)updateNotification:(const message_center::Notification*)notification;
+
 // Action for clicking on the notification's |closeButton_|.
 - (void)close:(id)sender;
 
 // Accessor for the notification.
 - (const message_center::Notification*)notification;
 
 // Gets the notification ID. This string is owned by the NotificationController
 // rather than the model object, so it's safe to use after the Notification has
 // been deleted.
 - (const std::string&)notificationID;
 
 @end
 
 #endif  // UI_MESSAGE_CENTER_COCOA_NOTIFICATION_CONTROLLER_H_