ui: Cleanup class/struct forward declarations

ui/message_center/views/notification_view.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_H_
 #define UI_MESSAGE_CENTER_VIEWS_NOTIFICATION_VIEW_H_
 
 #include <vector>
 
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "ui/message_center/message_center_export.h"
 #include "ui/message_center/views/message_view.h"
 #include "ui/views/view_targeter_delegate.h"
 
-class GURL;
-
 namespace views {
 class ProgressBar;
 }
 
 namespace message_center {
 
 class BoundedLabel;
-class MessageCenter;
 class NotificationButton;
-class PaddedButton;
 class ProportionalImageView;
 
 // View that displays all current types of notification (web, basic, image, and
 // list) except the custom notification. Future notification types may be
 // handled by other classes, in which case instances of those classes would be
 // returned by the Create() factory method below.
 class MESSAGE_CENTER_EXPORT NotificationView
     : public MessageView,
       public views::ViewTargeterDelegate {
  public:
@@ skipping 68 matching lines @@
   views::ProgressBar* progress_bar_view_ = nullptr;
   std::vector<NotificationButton*> action_buttons_;
   std::vector<views::View*> separators_;
 
   DISALLOW_COPY_AND_ASSIGN(NotificationView);
 };
 
 }  // namespace message_center
 
 #endif  // UI_MESSAGE_CENTER_VIEWS_NOTIFICATION_VIEW_H_