Made notification center notifications collapsed and expandable.

ui/message_center/message_popup_collection.h

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_MESSAGE_CENTER_MESSAGE_POPUP_COLLECTION_H_
 #define UI_MESSAGE_CENTER_MESSAGE_POPUP_COLLECTION_H_
 
 #include <list>
 #include <map>
 
 #include "base/timer.h"
 #include "ui/message_center/message_bubble_base.h"
 #include "ui/message_center/message_center_export.h"
-#include "ui/message_center/notification_list.h"
 #include "ui/views/widget/widget_observer.h"
 
 namespace views {
 class Widget;
 }
 
 namespace message_center {
 
+class MessageCenter;
 class ToastContentsView;
 
 // Container for popup toasts. Because each toast is a frameless window rather
 // than a view in a bubble, now the container just manages all of those windows.
 // This is similar to chrome/browser/notifications/balloon_collection, but the
 // contents of each toast are for the message center and layout strategy would
 // be slightly different.
 class MESSAGE_CENTER_EXPORT MessagePopupCollection
     : public views::WidgetObserver {
  public:
   // |context| specifies the context to create toast windows. It can be NULL
   // for non-aura environment. See comments in ui/views/widget/widget.h.
   MessagePopupCollection(gfx::NativeView context,
-                         NotificationList::Delegate* list_delegate);
+                         MessageCenter* message_center);
   virtual ~MessagePopupCollection();
 
   void UpdatePopups();
 
   void OnMouseEntered();
   void OnMouseExited();
 
  private:
   typedef std::map<std::string, ToastContentsView*> ToastContainer;
 
   void CloseAllWidgets();
 
-  // views::WidgetObserver overrides:
+  // Overridden from views::WidgetObserver:
   virtual void OnWidgetDestroying(views::Widget* widget) OVERRIDE;
 
   gfx::NativeView context_;
-  NotificationList::Delegate* list_delegate_;
+  MessageCenter* message_center_;
   ToastContainer toasts_;
 
   DISALLOW_COPY_AND_ASSIGN(MessagePopupCollection);
 };
 
 }  // namespace message_center
 
 #endif // UI_MESSAGE_CENTER_MESSAGE_POPUP_COLLECTION_H_