[cros,de-hack] Get rid of singleton for the WebUILoginScreen.

chrome/browser/automation/testing_automation_provider_chromeos.cc

 // Copyright (c) 2011 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/automation/testing_automation_provider.h"
 
 #include "base/command_line.h"
 #include "base/i18n/time_formatting.h"
 #include "base/stringprintf.h"
 #include "base/time.h"
@@ skipping 262 matching lines @@
 
   chromeos::ExistingUserController* controller =
       chromeos::ExistingUserController::current_controller();
 
   // Set up an observer (it will delete itself).
   new LoginObserver(controller, this, reply_message);
 
   if (CommandLine::ForCurrentProcess()->HasSwitch(switches::kWebUILogin)) {
     // WebUI login.
     chromeos::WebUILoginDisplay* webui_login_display =
-        chromeos::WebUILoginDisplay::GetInstance();
+        static_cast<chromeos::WebUILoginDisplay*>(controller->login_display());
     webui_login_display->ShowSigninScreenForCreds(username, password);
   } else {
     // Native UI login.
     controller->login_display()->SelectPod(0);
     controller->Login(username, password);
   }
 }
 
 void TestingAutomationProvider::LockScreen(DictionaryValue* args,
                                            IPC::Message* reply_message) {
@@ skipping 907 matching lines @@
   views::Widget* window = browser::CreateViewsWindow(
       browser->window()->GetNativeHandle(), take_photo_dialog);
   window->SetAlwaysOnTop(true);
   window->Show();
 }
 
 void TestingAutomationProvider::PowerChanged(
     const chromeos::PowerSupplyStatus& status) {
   power_status = status;
 }