Replace direct access to kGoogleServicesUsername with calls to SigninManager.

chrome/browser/supervised_user/custodian_profile_downloader_service_factory.cc

 // Copyright 2014 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/supervised_user/custodian_profile_downloader_service_factory.h"
 
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/signin/profile_oauth2_token_service_factory.h"
+#include "chrome/browser/signin/signin_manager_factory.h"
 #include "chrome/browser/supervised_user/custodian_profile_downloader_service.h"
 #include "components/keyed_service/content/browser_context_dependency_manager.h"
 
 // static
 CustodianProfileDownloaderService*
 CustodianProfileDownloaderServiceFactory::GetForProfile(
     Profile* profile) {
   return static_cast<CustodianProfileDownloaderService*>(
       GetInstance()->GetServiceForBrowserContext(profile, true));
 }
 
 // static
 CustodianProfileDownloaderServiceFactory*
 CustodianProfileDownloaderServiceFactory::GetInstance() {
   return Singleton<CustodianProfileDownloaderServiceFactory>::get();
 }
 
 CustodianProfileDownloaderServiceFactory::
 CustodianProfileDownloaderServiceFactory()
     : BrowserContextKeyedServiceFactory(
           "CustodianProfileDownloaderService",
           BrowserContextDependencyManager::GetInstance()) {
   // Indirect dependency via ProfileDownloader.
   DependsOn(ProfileOAuth2TokenServiceFactory::GetInstance());
+  DependsOn(SigninManagerFactory::GetInstance());
 }
 
 CustodianProfileDownloaderServiceFactory::
 ~CustodianProfileDownloaderServiceFactory() {}
 
 KeyedService* CustodianProfileDownloaderServiceFactory::BuildServiceInstanceFor(
     content::BrowserContext* profile) const {
   return new CustodianProfileDownloaderService(static_cast<Profile*>(profile));
 }