Cleanup: Remove unneeded chrome/common/pref_names.h includes.

chrome/browser/ui/webui/signin/login_ui_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/ui/webui/signin/login_ui_service_factory.h"
 
 #include "base/prefs/pref_service.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/webui/signin/login_ui_service.h"
-#include "chrome/common/pref_names.h"
 #include "components/keyed_service/content/browser_context_dependency_manager.h"
 #include "components/signin/core/browser/signin_manager.h"
 
 LoginUIServiceFactory::LoginUIServiceFactory()
     : BrowserContextKeyedServiceFactory(
         "LoginUIServiceFactory",
         BrowserContextDependencyManager::GetInstance()) {
 }
 
 LoginUIServiceFactory::~LoginUIServiceFactory() {}
 
 // static
 LoginUIService* LoginUIServiceFactory::GetForProfile(Profile* profile) {
   return static_cast<LoginUIService*>(
       GetInstance()->GetServiceForBrowserContext(profile, true));
 }
 
 // static
 LoginUIServiceFactory* LoginUIServiceFactory::GetInstance() {
   return Singleton<LoginUIServiceFactory>::get();
 }
 
 KeyedService* LoginUIServiceFactory::BuildServiceInstanceFor(
     content::BrowserContext* profile) const {
   return new LoginUIService(static_cast<Profile*>(profile));
 }