Allow partial update for notification update API

chrome/browser/notifications/balloon_collection_impl.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.
 
 // Handles the visible notification (or balloons).
 
 #ifndef CHROME_BROWSER_NOTIFICATIONS_BALLOON_COLLECTION_IMPL_H_
 #define CHROME_BROWSER_NOTIFICATIONS_BALLOON_COLLECTION_IMPL_H_
 
 #include <deque>
@@ skipping 28 matching lines @@
                             , public base::MessageLoopForUI::Observer
 #endif
 {
  public:
   BalloonCollectionImpl();
   virtual ~BalloonCollectionImpl();
 
   // BalloonCollection interface.
   virtual void Add(const Notification& notification,
                    Profile* profile) OVERRIDE;
-  virtual bool DoesIdExist(const std::string& id) OVERRIDE;
+  virtual const Notification* FindById(const std::string& id) const OVERRIDE;
   virtual bool RemoveById(const std::string& id) OVERRIDE;
   virtual bool RemoveBySourceOrigin(const GURL& source_origin) OVERRIDE;
   virtual bool RemoveByProfile(Profile* profile) OVERRIDE;
   virtual void RemoveAll() OVERRIDE;
   virtual bool HasSpace() const OVERRIDE;
   virtual void ResizeBalloon(Balloon* balloon, const gfx::Size& size) OVERRIDE;
   virtual void SetPositionPreference(PositionPreference position) OVERRIDE;
   virtual void DisplayChanged() OVERRIDE;
   virtual void OnBalloonClosed(Balloon* source) OVERRIDE;
   virtual const Balloons& GetActiveBalloons() OVERRIDE;
@@ skipping 179 matching lines @@
   base::WeakPtrFactory<BalloonCollectionImpl> reposition_factory_;
 
   // Is the balloon collection currently listening for UI events?
   bool added_as_message_loop_observer_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(BalloonCollectionImpl);
 };
 
 #endif  // CHROME_BROWSER_NOTIFICATIONS_BALLOON_COLLECTION_IMPL_H_