ios: Cleanup class/struct forward declarations

ios/chrome/browser/prefs/ios_chrome_pref_service_factory.h

 // Copyright 2015 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 IOS_CHROME_BROWSER_PREFS_IOS_CHROME_PREF_SERVICE_FACTORY_H_
 #define IOS_CHROME_BROWSER_PREFS_IOS_CHROME_PREF_SERVICE_FACTORY_H_
 
 #include <memory>
 
 #include "base/memory/ref_counted.h"
 
 class PrefRegistry;
 class PrefService;
-class PrefStore;
 
 namespace base {
 class FilePath;
 class SequencedTaskRunner;
 }
 
-namespace ios {
-class ChromeBrowserState;
-}
-
 namespace sync_preferences {
 class PrefServiceSyncable;
 }
 
 namespace user_prefs {
 class PrefRegistrySyncable;
 }
 
 // Factory methods that create and initialize a new instance of a PrefService
 // for Chrome on iOS with the applicable PrefStores. The |pref_filename| points
@@ skipping 10 matching lines @@
     base::SequencedTaskRunner* pref_io_task_runner,
     const scoped_refptr<user_prefs::PrefRegistrySyncable>& pref_registry);
 
 // Creates an incognito copy of |pref_service| that shares most prefs but uses
 // a fresh non-persistent overlay for the user pref store.
 std::unique_ptr<sync_preferences::PrefServiceSyncable>
 CreateIncognitoBrowserStatePrefs(
     sync_preferences::PrefServiceSyncable* main_pref_store);
 
 #endif  // IOS_CHROME_BROWSER_PREFS_IOS_CHROME_PREF_SERVICE_FACTORY_H_