Add flag to track migration from email to gaia id.

chrome/browser/signin/account_tracker_service_factory.cc

 // Copyright (c) 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/signin/account_tracker_service_factory.h"
 
 #include "base/memory/scoped_ptr.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/signin/profile_oauth2_token_service_factory.h"
 #include "components/keyed_service/content/browser_context_dependency_manager.h"
 #include "components/pref_registry/pref_registry_syncable.h"
 #include "components/signin/core/browser/account_tracker_service.h"
 #include "components/signin/core/browser/profile_oauth2_token_service.h"
+#include "components/signin/core/common/signin_pref_names.h"
 
 AccountTrackerServiceFactory::AccountTrackerServiceFactory()
     : BrowserContextKeyedServiceFactory(
         "AccountTrackerServiceFactory",
         BrowserContextDependencyManager::GetInstance()) {
   DependsOn(ProfileOAuth2TokenServiceFactory::GetInstance());
 }
 
 AccountTrackerServiceFactory::~AccountTrackerServiceFactory() {
 }
 
 // static
 AccountTrackerService*
 AccountTrackerServiceFactory::GetForProfile(Profile* profile) {
   return static_cast<AccountTrackerService*>(
       GetInstance()->GetServiceForBrowserContext(profile, true));
 }
 
 // static
 AccountTrackerServiceFactory* AccountTrackerServiceFactory::GetInstance() {
   return Singleton<AccountTrackerServiceFactory>::get();
 }
 
 void AccountTrackerServiceFactory::RegisterProfilePrefs(
     user_prefs::PrefRegistrySyncable* registry) {
   registry->RegisterListPref(
       AccountTrackerService::kAccountInfoPref,
       user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
+  registry->RegisterIntegerPref(
+      prefs::kAccountIdMigrationState,
+      AccountTrackerService::MIGRATION_NOT_STARTED,
+      user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
 }
 
 KeyedService* AccountTrackerServiceFactory::BuildServiceInstanceFor(
     content::BrowserContext* context) const {
   Profile* profile = static_cast<Profile*>(context);
   AccountTrackerService* service = new AccountTrackerService();
   service->Initialize(
       ProfileOAuth2TokenServiceFactory::GetForProfile(profile),
       profile->GetPrefs(),
       profile->GetRequestContext());
   return service;
 }