Move NotificationDelegate into message_center.

ui/message_center/notification_list.h

Index: ui/message_center/notification_list.h
diff --git a/ui/message_center/notification_list.h b/ui/message_center/notification_list.h
index 6a07d2c29255244bee17b5e9a2bf2f3255f2e33c..be57f5b8787b7065b2e36eface1c869bc037b34d 100644
--- a/ui/message_center/notification_list.h
+++ b/ui/message_center/notification_list.h
@@ -22,6 +22,9 @@ class DictionaryValue;
 }
 
 namespace message_center {
+
+class NotificationDelegate;
+
 namespace test {
 class NotificationListTest;
 }
@@ -61,7 +64,8 @@ class MESSAGE_CENTER_EXPORT NotificationList {
                        const string16& message,
                        const string16& display_source,
                        const std::string& extension_id,
-                       const base::DictionaryValue* optional_fields);
+                       const base::DictionaryValue* optional_fields,
+                       NotificationDelegate* delegate);
 
   void UpdateNotificationMessage(const std::string& old_id,
                                  const std::string& new_id,
@@ -115,6 +119,8 @@ class MESSAGE_CENTER_EXPORT NotificationList {
   // Marks the specified notification as expanded in the notification center.
   void MarkNotificationAsExpanded(const std::string& id);
 
+  NotificationDelegate* GetNotificationDelegate(const std::string& id);
+
   bool quiet_mode() const { return quiet_mode_; }
 
   // Sets the current quiet mode status to |quiet_mode|. The new status is not