Notificaitons refactor step 2

ui/message_center/message_view.h

Index: ui/message_center/message_view.h
diff --git a/ui/message_center/message_view.h b/ui/message_center/message_view.h
index be36eb4edc6bd6ff7d9dc89c164602dbd2f4c1f0..376f99a9e497c213a4f433f38a2de595852d31c8 100644
--- a/ui/message_center/message_view.h
+++ b/ui/message_center/message_view.h
@@ -30,7 +30,7 @@ class MessageView : public views::SlideOutView,
                     public views::ButtonListener {
  public:
   MessageView(NotificationList::Delegate* list_delegate,
-              const Notification& notification);
+              Notification* notification);
 
   virtual ~MessageView();
 
@@ -60,13 +60,13 @@ class MessageView : public views::SlideOutView,
   virtual void OnSlideOut() OVERRIDE;
 
   NotificationList::Delegate* list_delegate() { return list_delegate_; }
-  Notification& notification() { return notification_; }
+  Notification* notification() { return notification_; }
   views::ImageButton* close_button() { return close_button_.get(); }
   views::ScrollView* scroller() { return scroller_; }
 
  private:
-  NotificationList::Delegate* list_delegate_;
-  Notification notification_;
+  NotificationList::Delegate* list_delegate_; // Weak, global (MessageCenter).
+  Notification* notification_; // Weak, owned by NotificationList.
   scoped_ptr<views::ImageButton> close_button_;
 
   views::ScrollView* scroller_;