Use MountGuest to mount cryptohome for a demo user.

chrome/browser/chromeos/login/demo_mode/demo_app_launcher.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 "chrome/browser/chromeos/login/demo_mode/demo_app_launcher.h"
 
 #include "base/command_line.h"
 #include "chrome/browser/chromeos/app_mode/app_session_lifetime.h"
 #include "chrome/browser/chromeos/login/login_display_host_impl.h"
 #include "chrome/browser/chromeos/login/user_manager.h"
 #include "chrome/browser/extensions/component_loader.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/ui/extensions/application_launch.h"
 #include "chrome/common/chrome_switches.h"
 #include "extensions/browser/extension_system.h"
 #include "grit/browser_resources.h"
 
-namespace {
+namespace chromeos {
 
-const char kDemoAppUserId[] = "demouser@demo.app.local";
-
-}
-
-namespace chromeos {
+const char DemoAppLauncher::kDemoUserName[] = "demouser@demo.app.local";
 
 DemoAppLauncher::DemoAppLauncher() : profile_(NULL) {}
 
 DemoAppLauncher::~DemoAppLauncher() {}
 
 void DemoAppLauncher::StartDemoAppLaunch() {
   DVLOG(1) << "Launching demo app...";
   // user_id = DemoAppUserId, force_emphemeral = true, delegate = this.
   kiosk_profile_loader_.reset(
-      new KioskProfileLoader(kDemoAppUserId, true, this));
+      new KioskProfileLoader(kDemoUserName, true, this));
   kiosk_profile_loader_->Start();
 }
 
 // static
 bool DemoAppLauncher::IsDemoAppSession(const std::string& user_id) {
-  return user_id == kDemoAppUserId ? true : false;
+  return user_id == kDemoUserName ? true : false;
 }
 
 void DemoAppLauncher::OnProfileLoaded(Profile* profile) {
   DVLOG(1) << "Profile loaded... Starting demo app launch.";
   profile_ = profile;
 
   kiosk_profile_loader_.reset();
 
   // Load our demo app, then launch it.
   ExtensionService* extension_service =
@@ skipping 16 matching lines @@
   UserManager::Get()->SessionStarted();
 
   LoginDisplayHostImpl::default_host()->Finalize();
 }
 
 void DemoAppLauncher::OnProfileLoadFailed(KioskAppLaunchError::Error error) {
   LOG(ERROR) << "Loading the Kiosk Profile failed.";
 }
 
 }  // namespace chromeos