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 80 matching lines @@
   views::View* left_content_ = nullptr;
   views::View* right_content_ = nullptr;
 
   // Views which are dinamicallly created inside view hierarchy.
   views::Label* title_view_ = nullptr;
   BoundedLabel* message_view_ = nullptr;
   ProportionalImageView* icon_view_ = nullptr;
   views::View* image_container_ = nullptr;
   ProportionalImageView* image_view_ = nullptr;
   std::vector<views::LabelButton*> 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_