chrome: Cleanup class/struct forward declarations

chrome/browser/supervised_user/legacy/supervised_user_shared_settings_service.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_SUPERVISED_USER_LEGACY_SUPERVISED_USER_SHARED_SETTINGS_SERVICE_H_
 #define CHROME_BROWSER_SUPERVISED_USER_LEGACY_SUPERVISED_USER_SHARED_SETTINGS_SERVICE_H_
 
 #include <memory>
 #include <string>
 
 #include "base/callback.h"
 #include "base/callback_list.h"
 #include "chrome/browser/supervised_user/supervised_users.h"
 #include "components/keyed_service/core/keyed_service.h"
 #include "components/sync/model/syncable_service.h"
 
 class PrefService;
 
 namespace base {
-class DictionaryValue;
 class Value;
 }
 
 namespace user_prefs {
 class PrefRegistrySyncable;
 }
 
 // SupervisedUserSharedSettingsService syncs settings (as key-value pairs) that
 // can be modified both by a supervised user and their manager.
 // A supervised user can only modify their own settings, whereas a manager can
@@ skipping 75 matching lines @@
  private:
   std::unique_ptr<syncer::SyncChangeProcessor> sync_processor_;
   std::unique_ptr<syncer::SyncErrorFactory> error_handler_;
 
   ChangeCallbackList callbacks_;
 
   PrefService* prefs_;
 };
 
 #endif  // CHROME_BROWSER_SUPERVISED_USER_LEGACY_SUPERVISED_USER_SHARED_SETTINGS_SERVICE_H_