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

chromeos/cryptohome/mock_async_method_caller.cc

 // Copyright (c) 2012 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/cryptohome/mock_async_method_caller.h"
 
+#include "components/user_manager/user_id.h"
+
 using ::testing::Invoke;
 using ::testing::WithArgs;
 using ::testing::_;
 
 namespace cryptohome {
 
 const char MockAsyncMethodCaller::kFakeAttestationEnrollRequest[] = "enrollreq";
 const char MockAsyncMethodCaller::kFakeAttestationCertRequest[] = "certreq";
 const char MockAsyncMethodCaller::kFakeAttestationCert[] = "cert";
 const char MockAsyncMethodCaller::kFakeSanitizedUsername[] = "01234567890ABC";
@@ skipping 79 matching lines @@
     const DataCallback& callback) {
   callback.Run(success_, kFakeSanitizedUsername);
 }
 
 void MockAsyncMethodCaller::FakeEnterpriseChallenge(
     const DataCallback& callback) {
   callback.Run(success_, kFakeChallengeResponse);
 }
 
 }  // namespace cryptohome