When adding a supervised user, ensure the shelf position is at the bottom.

chrome/browser/chromeos/login/ui/webui_login_view.cc

Index: chrome/browser/chromeos/login/ui/webui_login_view.cc
diff --git a/chrome/browser/chromeos/login/ui/webui_login_view.cc b/chrome/browser/chromeos/login/ui/webui_login_view.cc
index b4acbd58deffcf24957f8c046ebcf36225e835cd..382140e9f52aacb55c9bd8d639377507dc543751 100644
--- a/chrome/browser/chromeos/login/ui/webui_login_view.cc
+++ b/chrome/browser/chromeos/login/ui/webui_login_view.cc
@@ -309,9 +309,9 @@ void WebUILoginView::OnPostponedShow() {
 void WebUILoginView::SetStatusAreaVisible(bool visible) {
   if (ash::Shell::GetInstance()->HasPrimaryStatusArea()) {
     ash::SystemTray* tray = ash::Shell::GetInstance()->GetPrimarySystemTray();
+    tray->SetVisible(visible);
     if (visible) {
       // Tray may have been initialized being hidden.
-      tray->SetVisible(visible);
       tray->GetWidget()->Show();
     } else {
       tray->GetWidget()->Hide();