We should use UserID object to identify users instead of username.

chrome/browser/chromeos/login/session/stub_login_session_manager_delegate.cc

Index: chrome/browser/chromeos/login/session/stub_login_session_manager_delegate.cc
diff --git a/chrome/browser/chromeos/login/session/stub_login_session_manager_delegate.cc b/chrome/browser/chromeos/login/session/stub_login_session_manager_delegate.cc
index b9f408383ed15bc1ee57435d7fe5e6142766e767..90279a4ce5fcd78d9623abab8116034a532a2894 100644
--- a/chrome/browser/chromeos/login/session/stub_login_session_manager_delegate.cc
+++ b/chrome/browser/chromeos/login/session/stub_login_session_manager_delegate.cc
@@ -9,12 +9,13 @@
 #include "chrome/browser/signin/signin_manager_factory.h"
 #include "chrome/common/pref_names.h"
 #include "components/signin/core/browser/signin_manager.h"
+#include "components/user_manager/user_id.h"
 
 namespace chromeos {
 
 StubLoginSessionManagerDelegate::StubLoginSessionManagerDelegate(
     Profile* profile,
-    const std::string& login_user_id)
+    const user_manager::UserID& login_user_id)
     : RestoreAfterCrashSessionManagerDelegate(profile, login_user_id) {
 }
 
@@ -26,7 +27,7 @@ void StubLoginSessionManagerDelegate::Start() {
 
   // For dev machines and stub user emulate as if sync has been initialized.
   SigninManagerFactory::GetForProfile(profile())
-      ->SetAuthenticatedAccountInfo(login_user_id(), login_user_id());
+      ->SetAuthenticatedAccountInfo(login_user_id().GetGaiaId(), login_user_id().GetUserEmail());
   RestoreAfterCrashSessionManagerDelegate::Start();
 }