Clean up old legacy preference migration logic.

chrome/browser/prefs/chrome_pref_service_factory.cc

 // Copyright (c) 2012 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.
 
 #include "chrome/browser/prefs/chrome_pref_service_factory.h"
 
 #include <stddef.h>
 
 #include <string>
 #include <vector>
@@ skipping 529 matching lines @@
 }
 
 void ClearResetTime(Profile* profile) {
   ProfilePrefStoreManager::ClearResetTime(profile->GetPrefs());
 }
 
 void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry) {
   ProfilePrefStoreManager::RegisterProfilePrefs(registry);
 }
 
-void RegisterPrefs(PrefRegistrySimple* registry) {
-  ProfilePrefStoreManager::RegisterPrefs(registry);
-}
-
 }  // namespace chrome_prefs