Add List notification support to new-style notification.

ui/message_center/views/notification_view_md.h

 // Copyright (c) 2012 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_VIEWS_NOTIFICATION_VIEW_MD_H_
 #define UI_MESSAGE_CENTER_VIEWS_NOTIFICATION_VIEW_MD_H_
 
 #include <vector>
 
 #include "base/gtest_prod_util.h"
@@ skipping 78 matching lines @@
   // Views in the bottom view
   views::View* bottom_view_ = nullptr;
 
   // Views in the floating controller
   std::unique_ptr<views::ImageButton> settings_button_;
   std::unique_ptr<views::ImageButton> close_button_;
   std::unique_ptr<views::ImageView> small_image_view_;
 
   std::vector<NotificationButton*> action_buttons_;
 
+  std::vector<views::View*> item_views_;
+
   DISALLOW_COPY_AND_ASSIGN(NotificationViewMD);
 };
 
 }  // namespace message_center
 
 #endif  // UI_MESSAGE_CENTER_VIEWS_NOTIFICATION_VIEW_MD_H_