chrome: Cleanup class/struct forward declarations

chrome/browser/chromeos/app_mode/kiosk_app_manager.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_CHROMEOS_APP_MODE_KIOSK_APP_MANAGER_H_
 #define CHROME_BROWSER_CHROMEOS_APP_MODE_KIOSK_APP_MANAGER_H_
 
 #include <map>
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "base/callback_forward.h"
 #include "base/lazy_instance.h"
 #include "base/macros.h"
 #include "base/observer_list.h"
 #include "base/time/time.h"
 #include "chrome/browser/chromeos/app_mode/kiosk_app_data_delegate.h"
 #include "chrome/browser/chromeos/extensions/external_cache.h"
 #include "chrome/browser/chromeos/settings/cros_settings.h"
 #include "chrome/browser/chromeos/settings/install_attributes.h"
 #include "components/signin/core/account_id/account_id.h"
 #include "ui/gfx/image/image_skia.h"
 
 class GURL;
 class PrefRegistrySimple;
 class Profile;
 
-namespace base {
-class RefCountedString;
-}
-
 namespace extensions {
 class Extension;
 class ExternalLoader;
 }
 
 namespace chromeos {
 
 class AppSession;
 class KioskAppData;
 class KioskAppExternalLoader;
@@ skipping 301 matching lines @@
   base::WeakPtr<KioskAppExternalLoader> secondary_app_external_loader_;
 
   std::unique_ptr<AppSession> app_session_;
 
   DISALLOW_COPY_AND_ASSIGN(KioskAppManager);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_APP_MODE_KIOSK_APP_MANAGER_H_