Introduce //components/user_prefs, use to eliminate c/b/prefs dependency in Autofill.

chrome/browser/prefs/pref_service_mock_builder.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/pref_service_mock_builder.h"
 
 #include "base/prefs/testing_pref_store.h"
-#include "chrome/browser/prefs/pref_registry_syncable.h"
+#include "components/user_prefs/pref_registry_syncable.h"
 
 PrefServiceMockBuilder::PrefServiceMockBuilder() {
   ResetDefaultState();
 }
 
 PrefServiceMockBuilder::~PrefServiceMockBuilder() {}
 
 PrefService* PrefServiceMockBuilder::Create(PrefRegistry* pref_registry) {
   PrefService* service = PrefServiceBuilder::Create(pref_registry);
   return service;
 }
 
 PrefServiceSyncable* PrefServiceMockBuilder::CreateSyncable(
     PrefRegistrySyncable* pref_registry) {
   PrefServiceSyncable* service =
       PrefServiceSyncableBuilder::CreateSyncable(pref_registry);
   return service;
 }
 
 void PrefServiceMockBuilder::ResetDefaultState() {
   user_prefs_ = new TestingPrefStore;
 }