Avoid including gtest file directly, and go through base instead

chrome/browser/chromeos/login/existing_user_controller.h

 // 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.
 
 #ifndef CHROME_BROWSER_CHROMEOS_LOGIN_EXISTING_USER_CONTROLLER_H_
 #define CHROME_BROWSER_CHROMEOS_LOGIN_EXISTING_USER_CONTROLLER_H_
 #pragma once
 
 #include <string>
 
 #include "base/compiler_specific.h"
+#include "base/gtest_prod_util.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/string16.h"
 #include "base/task.h"
 #include "base/timer.h"
 #include "chrome/browser/chromeos/login/captcha_view.h"
 #include "chrome/browser/chromeos/login/login_display.h"
 #include "chrome/browser/chromeos/login/login_performer.h"
 #include "chrome/browser/chromeos/login/login_utils.h"
 #include "chrome/browser/chromeos/login/ownership_status_checker.h"
 #include "chrome/browser/chromeos/login/password_changed_view.h"
 #include "chrome/browser/chromeos/login/user.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "googleurl/src/gurl.h"
-#include "testing/gtest/include/gtest/gtest_prod.h"
 #include "ui/gfx/rect.h"
 
 #if defined(TOOLKIT_USES_GTK)
 #include "chrome/browser/chromeos/legacy_window_manager/wm_message_listener.h"
 #endif
 
 namespace chromeos {
 
 class LoginDisplayHost;
 class CrosSettings;
@@ skipping 169 matching lines @@
   std::string display_email_;
 
   FRIEND_TEST_ALL_PREFIXES(ExistingUserControllerTest, NewUserLogin);
 
   DISALLOW_COPY_AND_ASSIGN(ExistingUserController);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_LOGIN_EXISTING_USER_CONTROLLER_H_