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

chrome/browser/chromeos/login/ui/webui_login_view.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/ui/webui_login_view.h"
 
 #include "ash/shell.h"
 #include "ash/system/tray/system_tray.h"
 #include "base/bind.h"
 #include "base/callback.h"
@@ skipping 291 matching lines @@
 }
 
 void WebUILoginView::OnPostponedShow() {
   set_is_hidden(false);
   OnLoginPromptVisible();
 }
 
 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();
     }
   }
 }
 
 void WebUILoginView::SetUIEnabled(bool enabled) {
   forward_keyboard_event_ = enabled;
   ash::SystemTray* tray = ash::Shell::GetInstance()->GetPrimarySystemTray();
@@ skipping 141 matching lines @@
   if (should_emit_login_prompt_visible_) {
     VLOG(1) << "Login WebUI >> login-prompt-visible";
     chromeos::DBusThreadManager::Get()->GetSessionManagerClient()->
         EmitLoginPromptVisible();
   }
 
   webui_visible_ = true;
 }
 
 }  // namespace chromeos