Add flag to track migration from email to gaia id.

components/signin/core/common/signin_pref_names.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 "components/signin/core/common/signin_pref_names.h"
 
 namespace prefs {
 
+// An integer property indicating the state of account id migration from
+// email to gaia id for the the profile.  See account_tracker_service.h
+// for possible values.
+const char kAccountIdMigrationState[] = "account_id_migration_state";
+
 // Boolean identifying whether reverse auto-login is enabled.
 const char kAutologinEnabled[] = "autologin.enabled";
 
 // String the identifies the last user that logged into sync and other
 // google services. As opposed to kGoogleServicesUsername, this value is not
 // cleared on signout, but while the user is signed in the two values will
 // be the same.
 const char kGoogleServicesLastUsername[] = "google.services.last_username";
 
 // Obfuscated account ID that identifies the current user logged into sync and
@@ skipping 25 matching lines @@
     "reverse_autologin.rejected_email_list";
 
 // Int64 which tracks, as time from epoch, when last time the user signed in
 // to the browser.
 const char kSignedInTime[] = "signin.signedin_time";
 
 // Boolean which stores if the user is allowed to signin to chrome.
 const char kSigninAllowed[] = "signin.allowed";
 
 }  // namespace prefs