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

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 "base/files/file_path.h"
 #include "base/logging.h"
 #include "chrome/browser/chromeos/app_mode/app_session_lifetime.h"
 #include "chrome/browser/chromeos/login/ui/login_display_host.h"
 #include "chrome/browser/chromeos/login/ui/login_display_host_impl.h"
 #include "chrome/browser/extensions/component_loader.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/lifetime/application_lifetime.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/extensions/app_launch_params.h"
 #include "chrome/browser/ui/extensions/application_launch.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/extensions/extension_constants.h"
 #include "chrome/grit/browser_resources.h"
 #include "chromeos/network/network_handler.h"
 #include "chromeos/network/network_state_handler.h"
 #include "components/user_manager/user_manager.h"
 #include "extensions/browser/extension_system.h"
 #include "extensions/common/constants.h"
 #include "extensions/common/extension.h"
 #include "ui/base/window_open_disposition.h"
 
+namespace {
+const char kDemoUserName[] = "demouser@demo.app.local";
+}
+
 namespace chromeos {
 
-const char DemoAppLauncher::kDemoUserName[] = "demouser@demo.app.local";
 const char DemoAppLauncher::kDemoAppId[] = "klimoghijjogocdbaikffefjfcfheiel";
 const base::FilePath::CharType kDefaultDemoAppPath[] =
     FILE_PATH_LITERAL("/usr/share/chromeos-assets/demo_app");
 
 // static
 base::FilePath* DemoAppLauncher::demo_app_path_ = NULL;
 
 DemoAppLauncher::DemoAppLauncher() {
   if (!demo_app_path_)
     demo_app_path_ = new base::FilePath(kDefaultDemoAppPath);
 }
 
 DemoAppLauncher::~DemoAppLauncher() {
   delete demo_app_path_;
 }
 
 void DemoAppLauncher::StartDemoAppLaunch() {
   DVLOG(1) << "Launching demo app...";
   // user_id = DemoAppUserId, force_emphemeral = true, delegate = this.
   kiosk_profile_loader_.reset(
-      new KioskProfileLoader(kDemoUserName, true, this));
+      new KioskProfileLoader(GetDemoUserID(), true, this));
   kiosk_profile_loader_->Start();
 }
 
 // static
-bool DemoAppLauncher::IsDemoAppSession(const std::string& user_id) {
-  return user_id == kDemoUserName;
+bool DemoAppLauncher::IsDemoAppSession(const user_manager::UserID& user_id) {
+  return user_id == GetDemoUserID();
 }
 
 // static
 void DemoAppLauncher::SetDemoAppPathForTesting(const base::FilePath& path) {
   delete demo_app_path_;
   demo_app_path_ = new base::FilePath(path);
 }
 
+// static
+user_manager::UserID DemoAppLauncher::GetDemoUserID() {
+  return user_manager::UserID::FromUserEmail(kDemoUserName);
+}
+
 void DemoAppLauncher::OnProfileLoaded(Profile* profile) {
   DVLOG(1) << "Profile loaded... Starting demo app launch.";
 
   kiosk_profile_loader_.reset();
 
   // Load our demo app, then launch it.
   ExtensionService* extension_service =
       extensions::ExtensionSystem::Get(profile)->extension_service();
   CHECK(demo_app_path_);
   const std::string extension_id = extension_service->component_loader()->Add(
@@ skipping 25 matching lines @@
 
   LoginDisplayHostImpl::default_host()->Finalize();
 }
 
 void DemoAppLauncher::OnProfileLoadFailed(KioskAppLaunchError::Error error) {
   LOG(ERROR) << "Loading the Kiosk Profile failed: " <<
       KioskAppLaunchError::GetErrorMessage(error);
 }
 
 }  // namespace chromeos