Use MountGuest to mount cryptohome for a demo user.

chrome/browser/chromeos/login/parallel_authenticator.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 "chrome/browser/chromeos/login/parallel_authenticator.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/files/file_path.h"
 #include "base/logging.h"
@@ skipping 330 matching lines @@
   SystemSaltGetter::Get()->GetSystemSalt(
       base::Bind(&Mount,
                  current_state_.get(),
                  scoped_refptr<ParallelAuthenticator>(this),
                  cryptohome::CREATE_IF_MISSING | cryptohome::ENSURE_EPHEMERAL));
 }
 
 void ParallelAuthenticator::LoginAsKioskAccount(
     const std::string& app_user_id, bool force_ephemeral) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  std::string user_id =
+      force_ephemeral ? UserManager::kGuestUserName : app_user_id;
   current_state_.reset(new AuthAttemptState(
-      UserContext(app_user_id,
+      UserContext(user_id,
                   std::string(),  // password
                   std::string()),  // auth_code
       std::string(),  // login_token
       std::string(),  // login_captcha
       User::USER_TYPE_KIOSK_APP,
       false));
+
   remove_user_data_on_failure_ = true;
-  int ephemeral_flag = force_ephemeral ? cryptohome::ENSURE_EPHEMERAL : 0;
-  MountPublic(current_state_.get(),
-        scoped_refptr<ParallelAuthenticator>(this),
-        cryptohome::CREATE_IF_MISSING | ephemeral_flag);
+  if (!force_ephemeral) {
+    MountPublic(current_state_.get(),
+          scoped_refptr<ParallelAuthenticator>(this),
+          cryptohome::CREATE_IF_MISSING);
+  } else {
+    ephemeral_mount_attempted_ = true;
+    MountGuest(current_state_.get(),
+               scoped_refptr<ParallelAuthenticator>(this));
+  }
 }
 
 void ParallelAuthenticator::OnRetailModeLoginSuccess() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   VLOG(1) << "Retail mode login success";
   // Send notification of success
   AuthenticationNotificationDetails details(true);
   content::NotificationService::current()->Notify(
       chrome::NOTIFICATION_LOGIN_AUTHENTICATION,
       content::NotificationService::AllSources(),
@@ skipping 433 matching lines @@
   Resolve();
 }
 
 void ParallelAuthenticator::SetOwnerState(bool owner_check_finished,
                                           bool check_result) {
   owner_is_verified_ = owner_check_finished;
   user_can_login_ = check_result;
 }
 
 }  // namespace chromeos