Adding implementation for MessageCenter::Delegate on MessageCeneterNotificationManager.

chrome/browser/notifications/notification_ui_manager.cc

Index: chrome/browser/notifications/notification_ui_manager.cc
diff --git a/chrome/browser/notifications/notification_ui_manager.cc b/chrome/browser/notifications/notification_ui_manager.cc
index 0006496b683641003eddcfeaa926fcd43468e052..1b09a48e763b29ad75279da5744f0ed339baf713 100644
--- a/chrome/browser/notifications/notification_ui_manager.cc
+++ b/chrome/browser/notifications/notification_ui_manager.cc
@@ -15,8 +15,14 @@
 
 // static
 bool NotificationUIManager::DelegatesToMessageCenter() {
+// MessageCenterNotificationManager doesn't work quite well with Ash
+// right now. Until it matures in ChromeOS, delegating to message center will
+// be done by BalloonCollectionImplAsh through BalloonNotificationUIManager.
+// TODO(mukai): remove this #if when that's no problem.
+#if !defined(USE_ASH)
   return CommandLine::ForCurrentProcess()->HasSwitch(
       switches::kEnableRichNotifications);
+#endif
   return false;
 }