Allow partial update for notification update API

chrome/browser/notifications/message_center_notification_manager.cc

Index: chrome/browser/notifications/message_center_notification_manager.cc
diff --git a/chrome/browser/notifications/message_center_notification_manager.cc b/chrome/browser/notifications/message_center_notification_manager.cc
index d0cbb7e7d14ee990070d5b1289ff378e1c853580..5c79cd92d0063d019917beea04567489d0a53e2d 100644
--- a/chrome/browser/notifications/message_center_notification_manager.cc
+++ b/chrome/browser/notifications/message_center_notification_manager.cc
@@ -64,12 +64,15 @@ MessageCenterNotificationManager::~MessageCenterNotificationManager() {
 ////////////////////////////////////////////////////////////////////////////////
 // NotificationUIManager
 
-bool MessageCenterNotificationManager::DoesIdExist(const std::string& id) {
-  if (NotificationUIManagerImpl::DoesIdExist(id))
+bool MessageCenterNotificationManager::DoesIdExist(
+    const std::string& id, Notification* matched_notification) {
+  if (NotificationUIManagerImpl::DoesIdExist(id, matched_notification))
     return true;
   NotificationMap::iterator iter = profile_notifications_.find(id);
   if (iter == profile_notifications_.end())
     return false;
+  if (matched_notification)
+    *matched_notification = iter->second->notification();
   return true;
 }