Allow partial update for notification update API

chrome/browser/notifications/balloon_notification_ui_manager.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_notification_ui_manager.h"
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/prefs/pref_service.h"
 #include "base/stl_util.h"
@@ skipping 26 matching lines @@
   DCHECK(!balloon_collection_.get() ||
          balloon_collection_->GetActiveBalloons().size() == 0);
   DCHECK(balloon_collection);
   balloon_collection_.reset(balloon_collection);
   balloon_collection_->SetPositionPreference(
       static_cast<BalloonCollection::PositionPreference>(
           position_pref_.GetValue()));
   balloon_collection_->set_space_change_listener(this);
 }
 
-bool BalloonNotificationUIManager::DoesIdExist(const std::string& id) {
-  if (NotificationUIManagerImpl::DoesIdExist(id))
-    return true;
-  return balloon_collection_->DoesIdExist(id);
+const Notification* BalloonNotificationUIManager::FindById(
+    const std::string& id) const {
+  const Notification* notification = NotificationUIManagerImpl::FindById(id);
+  if (notification)
+    return notification;
+  return balloon_collection_->FindById(id);
 }
 
 bool BalloonNotificationUIManager::CancelById(const std::string& id) {
   // See if this ID hasn't been shown yet.
   if (NotificationUIManagerImpl::CancelById(id))
     return true;
   // If it has been shown, remove it from the balloon collections.
   return balloon_collection_->RemoveById(id);
 }
 
@@ skipping 105 matching lines @@
     BalloonNotificationUIManager::GetInstanceForTesting() {
   if (NotificationUIManager::DelegatesToMessageCenter()) {
     LOG(ERROR) << "Attempt to run a test that requires "
                << "BalloonNotificationUIManager while delegating to a "
                << "native MessageCenter. Test will fail. Ask dimich@";
     return NULL;
   }
   return static_cast<BalloonNotificationUIManager*>(
       g_browser_process->notification_ui_manager());
 }