components: Cleanup class/struct fwd declarations

components/user_manager/known_user.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 COMPONENTS_USER_MANAGER_KNOWN_USER_H_
 #define COMPONENTS_USER_MANAGER_KNOWN_USER_H_
 
 #include <string>
 #include <vector>
 
 #include "components/user_manager/user_manager_export.h"
 
 class AccountId;
 class PrefRegistrySimple;
 
 namespace base {
 class DictionaryValue;
-class ListValue;
-class TaskRunner;
 }
 
 namespace user_manager {
 namespace known_user {
 // Methods for storage/retrieval of per-user properties in Local State.
 
 // Performs a lookup of properties associated with |account_id|. If found,
 // returns |true| and fills |out_value|. |out_value| can be NULL, if
 // only existence check is required.
 bool USER_MANAGER_EXPORT FindPrefs(const AccountId& account_id,
@@ skipping 106 matching lines @@
 // Removes all user preferences associated with |account_id|.
 // (This one used by user_manager only and thus not exported.)
 void RemovePrefs(const AccountId& account_id);
 
 // Register known user prefs.
 void USER_MANAGER_EXPORT RegisterPrefs(PrefRegistrySimple* registry);
 }
 }  // namespace user_manager
 
 #endif  // COMPONENTS_USER_MANAGER_KNOWN_USER_H_