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

chromeos/login/auth/fake_extended_authenticator.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 "chromeos/login/auth/fake_extended_authenticator.h"
 
 #include "base/logging.h"
 #include "chromeos/login/auth/auth_status_consumer.h"
 
 namespace chromeos {
@@ skipping 19 matching lines @@
 
 void FakeExtendedAuthenticator::SetConsumer(AuthStatusConsumer* consumer) {
   old_consumer_ = consumer;
 }
 
 void FakeExtendedAuthenticator::AuthenticateToMount(
     const UserContext& context,
     const ResultCallback& success_callback) {
   if (expected_user_context_ == context) {
     UserContext reported_user_context(context);
-    const std::string mount_hash = reported_user_context.GetUserID() + "-hash";
+    const std::string mount_hash = reported_user_context.GetUserID().GetUserEmail() + "-hash";
     reported_user_context.SetUserIDHash(mount_hash);
     if (!success_callback.is_null())
       success_callback.Run(mount_hash);
     OnAuthSuccess(reported_user_context);
     return;
   }
 
   OnAuthFailure(FAILED_MOUNT,
                 AuthFailure(AuthFailure::COULD_NOT_MOUNT_CRYPTOHOME));
 }
 
 void FakeExtendedAuthenticator::AuthenticateToCheck(
     const UserContext& context,
     const base::Closure& success_callback) {
   if (expected_user_context_ == context) {
     if (!success_callback.is_null())
       success_callback.Run();
     OnAuthSuccess(context);
     return;
   }
 
   OnAuthFailure(FAILED_MOUNT,
                 AuthFailure(AuthFailure::UNLOCK_FAILED));
 }
 
-void FakeExtendedAuthenticator::CreateMount(const std::string& user_id,
+void FakeExtendedAuthenticator::CreateMount(const user_manager::UserID& user_id,
                          const std::vector<cryptohome::KeyDefinition>& keys,
                          const ResultCallback& success_callback) {
   NOTREACHED();
 }
 
 void FakeExtendedAuthenticator::AddKey(const UserContext& context,
                     const cryptohome::KeyDefinition& key,
                     bool replace_existing,
                     const base::Closure& success_callback) {
   NOTREACHED();
@@ skipping 27 matching lines @@
 
 void FakeExtendedAuthenticator::OnAuthFailure(AuthState state,
                                               const AuthFailure& error) {
   if (consumer_)
     consumer_->OnAuthenticationFailure(state);
   if (old_consumer_)
     old_consumer_->OnAuthFailure(error);
 }
 
 }  // namespace chromeos