chrome: Cleanup class/struct forward declarations

chrome/browser/ui/views/message_center/message_center_frame_view.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 CHROME_BROWSER_UI_VIEWS_MESSAGE_CENTER_MESSAGE_CENTER_FRAME_VIEW_H_
 #define CHROME_BROWSER_UI_VIEWS_MESSAGE_CENTER_MESSAGE_CENTER_FRAME_VIEW_H_
 
 #include "base/macros.h"
 #include "ui/views/window/non_client_view.h"
 
-namespace views {
-class Label;
-class LabelButton;
-class BubbleBorder;
-}
-
 namespace message_center {
 
 // The non-client frame view of the message center widget.
 class MessageCenterFrameView : public views::NonClientFrameView {
  public:
   explicit MessageCenterFrameView();
   ~MessageCenterFrameView() override;
 
   // NonClientFrameView overrides:
   gfx::Rect GetBoundsForClientView() const override;
@@ skipping 10 matching lines @@
   gfx::Insets GetInsets() const override;
   const char* GetClassName() const override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(MessageCenterFrameView);
 };
 
 }  // namespace message_center
 
 #endif  // CHROME_BROWSER_UI_VIEWS_MESSAGE_CENTER_MESSAGE_CENTER_FRAME_VIEW_H_