chrome: Cleanup class/struct forward declarations

chrome/browser/ui/views/frame/web_app_left_header_view_ash.h

 // Copyright 2014 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_FRAME_WEB_APP_LEFT_HEADER_VIEW_ASH_H_
 #define CHROME_BROWSER_UI_VIEWS_FRAME_WEB_APP_LEFT_HEADER_VIEW_ASH_H_
 
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "ui/views/controls/button/button.h"
 
 class BrowserView;
 
 namespace ash {
 class FrameCaptionButton;
 }
 
-namespace views {
-class ImageButton;
-}
-
 // WebAppLeftHeaderView is a container view for any icons on the left of the
 // frame used for web app style windows. It contains a back button and a
 // location icon.
 class WebAppLeftHeaderView : public views::View,
                              public views::ButtonListener {
  public:
   static const char kViewClassName[];
 
   explicit WebAppLeftHeaderView(BrowserView* browser_view);
   ~WebAppLeftHeaderView() override;
@@ skipping 29 matching lines @@
   ash::FrameCaptionButton* back_button_;
 
   // The location icon indicator. Shows the connection security status and
   // allows the user to bring up the website settings dialog.
   ash::FrameCaptionButton* location_icon_;
 
   DISALLOW_COPY_AND_ASSIGN(WebAppLeftHeaderView);
 };
 
 #endif  // CHROME_BROWSER_UI_VIEWS_FRAME_WEB_APP_LEFT_HEADER_VIEW_ASH_H_