This CL replaces std::string user_id in ash/* with AccountId.

chrome/browser/ui/views/frame/system_menu_model_builder.cc

Index: chrome/browser/ui/views/frame/system_menu_model_builder.cc
diff --git a/chrome/browser/ui/views/frame/system_menu_model_builder.cc b/chrome/browser/ui/views/frame/system_menu_model_builder.cc
index a1198fe396a6022fbe6b1f90ad477ac1d477c6c6..ea0d1cbc0de9d3b02f77493781b67415fcaefeb2 100644
--- a/chrome/browser/ui/views/frame/system_menu_model_builder.cc
+++ b/chrome/browser/ui/views/frame/system_menu_model_builder.cc
@@ -23,6 +23,7 @@
 #include "chrome/browser/ui/ash/multi_user/multi_user_util.h"
 #include "chrome/browser/ui/ash/multi_user/multi_user_window_manager.h"
 #include "chrome/browser/ui/browser_window.h"
+#include "components/signin/core/account_id/account_id.h"
 #include "components/user_manager/user_info.h"
 #include "ui/base/l10n/l10n_util.h"
 #endif
@@ -169,10 +170,11 @@ void SystemMenuModelBuilder::AppendTeleportMenu(ui::SimpleMenuModel* model) {
   // is not owned by anyone, we don't show the menu addition.
   chrome::MultiUserWindowManager* manager =
       chrome::MultiUserWindowManager::GetInstance();
-  const std::string user_id =
-      multi_user_util::GetUserIDFromProfile(browser()->profile());
+  const AccountId account_id =
+      multi_user_util::GetAccountIdFromProfile(browser()->profile());
   aura::Window* window = browser()->window()->GetNativeWindow();
-  if (user_id.empty() || !window || manager->GetWindowOwner(window).empty())
+  if (!account_id.is_valid() || !window ||
+      !manager->GetWindowOwner(window).is_valid())
     return;
 
   model->AddSeparator(ui::NORMAL_SEPARATOR);