Remove the most obvious dead code from message center.

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 54 matching lines @@
         'notifier_settings.cc',
         'notifier_settings.h',
         'views/bounded_label.cc',
         'views/bounded_label.h',
         'views/message_bubble_base.cc',
         'views/message_bubble_base.h',
         'views/message_center_bubble.cc',
         'views/message_center_bubble.h',
         'views/message_center_view.cc',
         'views/message_center_view.h',
-        'views/message_popup_bubble.cc',
-        'views/message_popup_bubble.h',
         'views/message_popup_collection.cc',
         'views/message_popup_collection.h',
-        'views/message_simple_view.cc',
-        'views/message_simple_view.h',
         'views/message_view.cc',
         'views/message_view.h',
         'views/notifier_settings_view.cc',
         'views/notifier_settings_view.h',
         'views/notification_view.cc',
         'views/notification_view.h',
         'views/toast_contents_view.cc',
         'views/toast_contents_view.h',
       ],
       # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
@@ skipping 100 matching lines @@
           'sources/': [
             # Exclude everything except main().
             ['exclude', '\\.(cc|mm)$'],
             ['include', '^test/run_all_unittests\\.cc$'],
           ],
         }],
       ],
     },  # target_name: message_center_unittests
   ],
 }