Adding NOTREACHED to see if any of the methods are called

ui/message_center/notification_delegate.cc

Index: ui/message_center/notification_delegate.cc
diff --git a/ui/message_center/notification_delegate.cc b/ui/message_center/notification_delegate.cc
index 70675233293179c66f636f56be93e89e35492d9e..05157710f6cbb0d0f9a8e12b53fc9c50a020f7ce 100644
--- a/ui/message_center/notification_delegate.cc
+++ b/ui/message_center/notification_delegate.cc
@@ -10,15 +10,26 @@ namespace message_center {
 
 // NotificationDelegate:
 
-void NotificationDelegate::Display() {}
+void NotificationDelegate::Display() {
+  NOTREACHED();
+}
 
-void NotificationDelegate::Close(bool by_user) {}
+void NotificationDelegate::Close(bool by_user) {
+  NOTREACHED();
+}
 
-bool NotificationDelegate::HasClickedListener() { return false; }
+bool NotificationDelegate::HasClickedListener() {
+  NOTREACHED();
+  return false;
+}
 
-void NotificationDelegate::Click() {}
+void NotificationDelegate::Click() {
+  NOTREACHED();
+}
 
-void NotificationDelegate::ButtonClick(int button_index) {}
+void NotificationDelegate::ButtonClick(int button_index) {
+  NOTREACHED();
+}
 
 void NotificationDelegate::ButtonClickWithReply(int button_index,
                                                 const base::string16& reply) {