Move knowledge about MessageCenter out of MessageView.

ui/message_center/views/notification_view.h

Index: ui/message_center/views/notification_view.h
diff --git a/ui/message_center/views/notification_view.h b/ui/message_center/views/notification_view.h
index c27037b0cfd67819f2d0a5280d404f0469a06484..69529ed972ee3e84cff7ed7a10e6e93e9a964321 100644
--- a/ui/message_center/views/notification_view.h
+++ b/ui/message_center/views/notification_view.h
@@ -53,12 +53,21 @@ class MESSAGE_CENTER_EXPORT NotificationView : public MessageView {
   virtual void ButtonPressed(views::Button* sender,
                              const ui::Event& event) OVERRIDE;
 
+  std::string notification_id() { return notification_id_; }
+
  protected:
   NotificationView(const Notification& notification,
                    MessageCenter* message_center,
                    MessageCenterTray* tray,
                    bool expanded);
 
+  // Overrides from base class MessageView:
+  virtual MessageViewTypes GetType() OVERRIDE;
+  virtual void ClickOnNotification() OVERRIDE;
+  virtual void RemoveNotification(bool by_user) OVERRIDE;
+  virtual void DisableNotificationsFromThisSource() OVERRIDE;
+  virtual void ShowNotifierSettingsBubble() OVERRIDE;
+
  private:
   bool IsExpansionNeeded(int width);
   bool IsMessageExpansionNeeded(int width);
@@ -66,6 +75,11 @@ class MESSAGE_CENTER_EXPORT NotificationView : public MessageView {
   int GetMessageLines(int width, int limit);
   int GetMessageHeight(int width, int limit);
 
+  MessageCenter* message_center_;  // Weak.
+  MessageCenterTray* tray_;  // Weak.
+  std::string notification_id_;
+  message_center::NotifierId notifier_id_;
+
   // Describes whether the view should display a hand pointer or not.
   bool clickable_;
   bool is_expanded_;