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

chromeos/login/auth/cryptohome_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/cryptohome_authenticator.h"
 
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/bind.h"
@@ skipping 275 matching lines @@
   cryptohome::AsyncMethodCaller::GetInstance()->AsyncGetSanitizedUsername(
       attempt->user_context.GetUserID(),
       base::Bind(&TriggerResolveHash, attempt, resolver));
 }
 
 // Calls cryptohome's MountPublic method
 void MountPublic(const base::WeakPtr<AuthAttemptState>& attempt,
                  scoped_refptr<CryptohomeAuthenticator> resolver,
                  int flags) {
   cryptohome::AsyncMethodCaller::GetInstance()->AsyncMountPublic(
-      attempt->user_context.GetUserID(),
+      attempt->user_context.GetUserID().GetUserEmail(),
       flags,
       base::Bind(&TriggerResolveWithLoginTimeMarker,
                  "CryptohomeMountPublic-End",
                  attempt,
                  resolver));
   cryptohome::AsyncMethodCaller::GetInstance()->AsyncGetSanitizedUsername(
       attempt->user_context.GetUserID(),
       base::Bind(&TriggerResolveHash, attempt, resolver));
 }
 
@@ skipping 145 matching lines @@
   remove_user_data_on_failure_ = false;
   StartMount(current_state_->AsWeakPtr(),
              scoped_refptr<CryptohomeAuthenticator>(this),
              false /* ephemeral */, false /* create_if_nonexistent */);
 }
 
 void CryptohomeAuthenticator::LoginOffTheRecord() {
   DCHECK(task_runner_->RunsTasksOnCurrentThread());
   current_state_.reset(
       new AuthAttemptState(UserContext(user_manager::USER_TYPE_GUEST,
-                                       chromeos::login::kGuestUserName),
+                                       chromeos::login::GetGuestUserID()),
                            false,    // unlock
                            false,    // online_complete
                            false));  // user_is_new
   remove_user_data_on_failure_ = false;
   ephemeral_mount_attempted_ = true;
   MountGuestAndGetHash(current_state_->AsWeakPtr(),
                        scoped_refptr<CryptohomeAuthenticator>(this));
 }
 
 void CryptohomeAuthenticator::LoginAsPublicSession(
     const UserContext& user_context) {
   DCHECK(task_runner_->RunsTasksOnCurrentThread());
   DCHECK_EQ(user_manager::USER_TYPE_PUBLIC_ACCOUNT, user_context.GetUserType());
 
   current_state_.reset(
       new AuthAttemptState(user_context,
                            false,    // unlock
                            false,    // online_complete
                            false));  // user_is_new
   remove_user_data_on_failure_ = false;
   ephemeral_mount_attempted_ = true;
   StartMount(current_state_->AsWeakPtr(),
              scoped_refptr<CryptohomeAuthenticator>(this), true /* ephemeral */,
              true /* create_if_nonexistent */);
 }
 
 void CryptohomeAuthenticator::LoginAsKioskAccount(
-    const std::string& app_user_id,
+    const user_manager::UserID& app_user_id,
     bool use_guest_mount) {
   DCHECK(task_runner_->RunsTasksOnCurrentThread());
 
-  const std::string user_id =
-      use_guest_mount ? chromeos::login::kGuestUserName : app_user_id;
+  const user_manager::UserID user_id =
+      use_guest_mount ? chromeos::login::GetGuestUserID() : app_user_id;
   current_state_.reset(new AuthAttemptState(
       UserContext(user_manager::USER_TYPE_KIOSK_APP, user_id),
       false,    // unlock
       false,    // online_complete
       false));  // user_is_new
 
   remove_user_data_on_failure_ = true;
   if (!use_guest_mount) {
     MountPublic(current_state_->AsWeakPtr(),
                 scoped_refptr<CryptohomeAuthenticator>(this),
@@ skipping 374 matching lines @@
   Resolve();
 }
 
 void CryptohomeAuthenticator::SetOwnerState(bool owner_check_finished,
                                             bool check_result) {
   owner_is_verified_ = owner_check_finished;
   user_can_login_ = check_result;
 }
 
 }  // namespace chromeos