Allow partial update for notification update API

chrome/browser/notifications/balloon_notification_ui_manager.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_NOTIFICATIONS_BALLOON_NOTIFICATION_UI_MANAGER_H_
 #define CHROME_BROWSER_NOTIFICATIONS_BALLOON_NOTIFICATION_UI_MANAGER_H_
 
 #include <string>
 
 #include "base/memory/scoped_ptr.h"
@@ skipping 16 matching lines @@
       public BalloonCollection::BalloonSpaceChangeListener {
  public:
   explicit BalloonNotificationUIManager(PrefService* local_state);
   virtual ~BalloonNotificationUIManager();
 
   // Initializes the UI manager with a balloon collection; this object
   // takes ownership of the balloon collection.
   void SetBalloonCollection(BalloonCollection* balloon_collection);
 
   // NotificationUIManager:
-  virtual bool DoesIdExist(const std::string& notification_id) OVERRIDE;
+  virtual const Notification* FindById(
+      const std::string& notification_id) const OVERRIDE;
   virtual bool CancelById(const std::string& notification_id) OVERRIDE;
   virtual std::set<std::string> GetAllIdsByProfileAndSourceOrigin(
       Profile* profile,
       const GURL& source) OVERRIDE;
   virtual bool CancelAllBySourceOrigin(const GURL& source_origin) OVERRIDE;
   virtual bool CancelAllByProfile(Profile* profile) OVERRIDE;
   virtual void CancelAll() OVERRIDE;
 
   // NotificationUIManagerImpl:
   virtual bool ShowNotification(const Notification& notification,
@@ skipping 23 matching lines @@
   // An owned pointer to the collection of active balloons.
   scoped_ptr<BalloonCollection> balloon_collection_;
 
   // Prefs listener for the position preference.
   IntegerPrefMember position_pref_;
 
   DISALLOW_COPY_AND_ASSIGN(BalloonNotificationUIManager);
 };
 
 #endif  // CHROME_BROWSER_NOTIFICATIONS_BALLOON_NOTIFICATION_UI_MANAGER_H_