Allow partial update for notification update API

chrome/browser/notifications/balloon_collection_impl.cc

 // 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.
 
 #include "chrome/browser/notifications/balloon_collection_impl.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/stl_util.h"
 #include "chrome/browser/chrome_notification_types.h"
@@ skipping 74 matching lines @@
   // This is used only for testing.
   if (!on_collection_changed_callback_.is_null())
     on_collection_changed_callback_.Run();
 }
 
 void BalloonCollectionImpl::Add(const Notification& notification,
                                 Profile* profile) {
   AddImpl(notification, profile, false);
 }
 
-bool BalloonCollectionImpl::DoesIdExist(const std::string& id) {
-  return base_.DoesIdExist(id);
+const Notification* BalloonCollectionImpl::FindById(
+    const std::string& id) const {
+  return base_.FindById(id);
 }
 
 bool BalloonCollectionImpl::RemoveById(const std::string& id) {
   return base_.CloseById(id);
 }
 
 bool BalloonCollectionImpl::RemoveBySourceOrigin(const GURL& origin) {
   return base_.CloseAllBySourceOrigin(origin);
 }
 
@@ skipping 371 matching lines @@
       gfx::Screen::GetNativeScreen()->GetPrimaryDisplay().work_area();
 #endif
   if (work_area_ != new_work_area) {
     work_area_.SetRect(new_work_area.x(), new_work_area.y(),
                        new_work_area.width(), new_work_area.height());
     changed = true;
   }
 
   return changed;
 }