extensions: Cleanup class/struct fwd declarations

extensions/components/native_app_window/native_app_window_views.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 EXTENSIONS_COMPONENTS_NATIVE_APP_WINDOW_NATIVE_APP_WINDOW_VIEWS_H_
 #define EXTENSIONS_COMPONENTS_NATIVE_APP_WINDOW_NATIVE_APP_WINDOW_VIEWS_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "base/observer_list.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "extensions/browser/app_window/app_window.h"
 #include "extensions/browser/app_window/native_app_window.h"
 #include "extensions/browser/app_window/size_constraints.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/views/controls/webview/unhandled_keyboard_event_handler.h"
 #include "ui/views/widget/widget.h"
 #include "ui/views/widget/widget_delegate.h"
 #include "ui/views/widget/widget_observer.h"
 
 class SkRegion;
 
 namespace content {
-class BrowserContext;
 class RenderViewHost;
-class WebContents;
-}
-
-namespace extensions {
-class Extension;
-}
-
-namespace ui {
-class MenuModel;
 }
 
 namespace views {
-class MenuRunner;
 class WebView;
 }
 
 namespace native_app_window {
 
 // A NativeAppWindow backed by a views::Widget. This class may be used alone
 // as a stub or subclassed (for example, ChromeNativeAppWindowViews).
 class NativeAppWindowViews : public extensions::NativeAppWindow,
                              public content::WebContentsObserver,
                              public views::WidgetDelegateView,
@@ skipping 133 matching lines @@
   views::UnhandledKeyboardEventHandler unhandled_keyboard_event_handler_;
 
   base::ObserverList<web_modal::ModalDialogHostObserver> observer_list_;
 
   DISALLOW_COPY_AND_ASSIGN(NativeAppWindowViews);
 };
 
 }  // namespace native_app_window
 
 #endif  // EXTENSIONS_COMPONENTS_NATIVE_APP_WINDOW_NATIVE_APP_WINDOW_VIEWS_H_