This CL replaces e-mail with AccountId on user selection screen.

chrome/browser/chromeos/login/screens/user_selection_screen.cc

Index: chrome/browser/chromeos/login/screens/user_selection_screen.cc
diff --git a/chrome/browser/chromeos/login/screens/user_selection_screen.cc b/chrome/browser/chromeos/login/screens/user_selection_screen.cc
index 37bb77bf9cd5c5e1fd7236b4b4e9b7a4c8c43178..9b71105607f85044d4869aeaa3fffef3f7f54e66 100644
--- a/chrome/browser/chromeos/login/screens/user_selection_screen.cc
+++ b/chrome/browser/chromeos/login/screens/user_selection_screen.cc
@@ -148,7 +148,7 @@ void UserSelectionScreen::FillUserDictionary(
       user->GetType() == user_manager::USER_TYPE_SUPERVISED;
   const bool is_child_user = user->GetType() == user_manager::USER_TYPE_CHILD;
 
-  user_dict->SetString(kKeyUsername, user->GetAccountId().GetUserEmail());
+  user_dict->SetString(kKeyUsername, user->GetAccountId().Serialize());
   user_dict->SetString(kKeyEmailAddress, user->display_email());
   user_dict->SetString(kKeyDisplayName, user->GetDisplayName());
   user_dict->SetBoolean(kKeyPublicAccount, is_public_session);