Cleanup: Remove unneeded forward declarations from chrome/browser/chromeos.

chrome/browser/chromeos/frame/bubble_window_views.h

 // Copyright (c) 2011 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_CHROMEOS_FRAME_BUBBLE_WINDOW_VIEWS_H_
 #define CHROME_BROWSER_CHROMEOS_FRAME_BUBBLE_WINDOW_VIEWS_H_
 #pragma once
 
 #include "chrome/browser/chromeos/frame/bubble_window_style.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "views/widget/widget.h"
 
-namespace views {
-class WidgetDelegate;
-}
-
 namespace chromeos {
 
 // A window that uses BubbleFrameView as its frame.
 class BubbleWindowViews : public views::Widget {
  public:
   void SetBackgroundColor();
 
  protected:
   explicit BubbleWindowViews(BubbleWindowStyle style);
   virtual views::NonClientFrameView* CreateNonClientFrameView() OVERRIDE;
 
  private:
   friend class BubbleWindow;
   BubbleWindowStyle style_;
 
   DISALLOW_COPY_AND_ASSIGN(BubbleWindowViews);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_FRAME_BUBBLE_WINDOW_VIEWS_H_