Added browser test for existing user controller (new user login).

chrome/browser/chromeos/login/wizard_in_process_browser_test.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/chromeos/login/wizard_in_process_browser_test.h"
 
 #include "base/message_loop.h"
 #include "chrome/browser/chromeos/login/wizard_controller.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/views/browser_dialogs.h"
 #include "chrome/test/ui_test_utils.h"
 
 namespace chromeos {
 
 WizardInProcessBrowserTest::WizardInProcessBrowserTest(const char* screen_name)
     : screen_name_(screen_name),
       controller_(NULL) {
 }
 
 Browser* WizardInProcessBrowserTest::CreateBrowser(Profile* profile) {
   SetUpWizard();
 
-  browser::ShowLoginWizard(screen_name_.c_str(), gfx::Size(1024, 600));
-  controller_ = WizardController::default_controller();
+  if (!screen_name_.empty()) {
+    browser::ShowLoginWizard(screen_name_.c_str(), gfx::Size(1024, 600));
+    controller_ = WizardController::default_controller();
+  }
   return NULL;
 }
 
 void WizardInProcessBrowserTest::CleanUpOnMainThread() {
   delete controller_;
 
   // Observers and what not are notified after the views are deleted, which
   // happens after a delay (because they are contained in a WidgetGtk which
   // delays deleting itself). Run the message loop until we know the wizard
   // has been deleted.
   ui_test_utils::WaitForNotification(
       NotificationType::WIZARD_CONTENT_VIEW_DESTROYED);
 }
 
 }  // namespace chromeos