Componentize more signin code

components/signin/core/browser/account_tracker_service.cc

Index: components/signin/core/browser/account_tracker_service.cc
diff --git a/components/signin/core/browser/account_tracker_service.cc b/components/signin/core/browser/account_tracker_service.cc
index 072bb7a09f2a89adecc7674346199c488be12de3..6243341d12b0961a41beef4002fc2c945121b024 100644
--- a/components/signin/core/browser/account_tracker_service.cc
+++ b/components/signin/core/browser/account_tracker_service.cc
@@ -12,6 +12,7 @@
 #include "base/strings/string_split.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/trace_event/trace_event.h"
+#include "components/pref_registry/pref_registry_syncable.h"
 #include "components/signin/core/browser/signin_client.h"
 #include "components/signin/core/browser/signin_manager.h"
 #include "components/signin/core/common/signin_pref_names.h"
@@ -54,6 +55,14 @@ AccountTrackerService::AccountTrackerService()
 AccountTrackerService::~AccountTrackerService() {
 }
 
+// static
+void AccountTrackerService::RegisterPrefs(
+    user_prefs::PrefRegistrySyncable* registry) {
+  registry->RegisterListPref(AccountTrackerService::kAccountInfoPref);
+  registry->RegisterIntegerPref(prefs::kAccountIdMigrationState,
+                                AccountTrackerService::MIGRATION_NOT_STARTED);
+}
+
 void AccountTrackerService::Initialize(SigninClient* signin_client) {
   DCHECK(signin_client);
   DCHECK(!signin_client_);