ui: Cleanup class/struct forward declarations

ui/message_center/views/message_center_button_bar.h

 // Copyright 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_VIEWS_MESSAGE_CENTER_BUTTON_BAR_H_
 #define UI_MESSAGE_CENTER_VIEWS_MESSAGE_CENTER_BUTTON_BAR_H_
 
 #include "base/macros.h"
 #include "build/build_config.h"
 #include "ui/message_center/message_center_export.h"
 #include "ui/views/controls/button/button.h"
 #include "ui/views/controls/button/image_button.h"
 #include "ui/views/view.h"
 
 namespace views {
 class Label;
 }
 
 namespace message_center {
 
-class ButtonBarSettingsLabel;
 class MessageCenter;
-class MessageCenterTray;
 class MessageCenterView;
 class NotificationCenterButton;
 class NotifierSettingsProvider;
 
 // MessageCenterButtonBar is the class that shows the content outside the main
 // notification area - the label (or NotifierGroup switcher) and the buttons.
 class MessageCenterButtonBar : public views::View,
                                public views::ButtonListener {
  public:
   MessageCenterButtonBar(MessageCenterView* message_center_view,
@@ skipping 53 matching lines @@
   NotificationCenterButton* close_all_button_;
   NotificationCenterButton* settings_button_;
   NotificationCenterButton* quiet_mode_button_;
 
   DISALLOW_COPY_AND_ASSIGN(MessageCenterButtonBar);
 };
 
 }  // namespace message_center
 
 #endif  // UI_MESSAGE_CENTER_VIEWS_MESSAGE_CENTER_BUTTON_BAR_H_