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

chrome/browser/chromeos/app_mode/app_session_lifetime.cc

Index: chrome/browser/chromeos/app_mode/app_session_lifetime.cc
diff --git a/chrome/browser/chromeos/app_mode/app_session_lifetime.cc b/chrome/browser/chromeos/app_mode/app_session_lifetime.cc
index 741a1c13e6d802a15c37749b19517fccffcb614c..a51f3948732dcdcc4eeab8d1acf36c592d6ff98e 100644
--- a/chrome/browser/chromeos/app_mode/app_session_lifetime.cc
+++ b/chrome/browser/chromeos/app_mode/app_session_lifetime.cc
@@ -25,6 +25,7 @@
 #include "chrome/common/pref_names.h"
 #include "chromeos/network/network_state.h"
 #include "chromeos/network/network_state_handler.h"
+#include "components/user_manager/user_id.h"
 #include "components/user_manager/user_manager.h"
 #include "content/public/browser/web_contents.h"
 #include "extensions/browser/app_window/app_window.h"
@@ -57,7 +58,7 @@ class AppWindowHandler : public AppWindowRegistry::Observer {
   void OnAppWindowRemoved(AppWindow* app_window) override {
     if (window_registry_->GetAppWindowsForApp(app_id_).empty()) {
       if (DemoAppLauncher::IsDemoAppSession(
-              user_manager::UserManager::Get()->GetActiveUser()->email())) {
+              user_manager::UserManager::Get()->GetActiveUser()->GetUserID())) {
         // If we were in demo mode, we disabled all our network technologies,
         // re-enable them.
         NetworkStateHandler* handler =
@@ -131,7 +132,7 @@ void InitAppSession(Profile* profile, const std::string& app_id) {
   // For a demo app, we don't need to either setup the update service or
   // the idle app name notification.
   if (DemoAppLauncher::IsDemoAppSession(
-          user_manager::UserManager::Get()->GetActiveUser()->email()))
+          user_manager::UserManager::Get()->GetActiveUser()->GetUserID()))
     return;
 
   // Set the app_id for the current instance of KioskAppUpdateService.