Pull MessageListView into its own file for easier testing.

ui/message_center/message_center.gyp

 # 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
   'targets': [
     {
@@ skipping 69 matching lines @@
         'views/desktop_popup_alignment_delegate.h',
         'views/message_bubble_base.cc',
         'views/message_bubble_base.h',
         'views/message_center_bubble.cc',
         'views/message_center_bubble.h',
         'views/message_center_button_bar.cc',
         'views/message_center_button_bar.h',
         'views/message_center_controller.h',
         'views/message_center_view.cc',
         'views/message_center_view.h',
+        'views/message_list_view.cc',
+        'views/message_list_view.h',
         'views/message_popup_collection.cc',
         'views/message_popup_collection.h',
         'views/message_view.cc',
         'views/message_view.h',
         'views/message_view_context_menu_controller.cc',
         'views/message_view_context_menu_controller.h',
         'views/notification_button.cc',
         'views/notification_button.h',
         'views/notification_view.cc',
         'views/notification_view.h',
@@ skipping 175 matching lines @@
               'dependencies': [
                 '../../tools/xdisplaycheck/xdisplaycheck.gyp:xdisplaycheck',
               ],
             }],
           ],
         },
       ],
     }],
   ],
 }