cros: Remove unused method

chrome/browser/chromeos/login/screens/error_screen.h

 // Copyright (c) 2012 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_SCREENS_ERROR_SCREEN_H_
 #define CHROME_BROWSER_CHROMEOS_LOGIN_SCREENS_ERROR_SCREEN_H_
 
 #include <memory>
 
 #include "base/compiler_specific.h"
@@ skipping 15 matching lines @@
 // Controller for the error screen.
 class ErrorScreen : public NetworkErrorModel, public LoginPerformer::Delegate {
  public:
   typedef std::unique_ptr<base::CallbackList<void()>::Subscription>
       ConnectRequestCallbackSubscription;
 
   ErrorScreen(BaseScreenDelegate* base_screen_delegate, NetworkErrorView* view);
   ~ErrorScreen() override;
 
   // NetworkErrorModel:
-  void PrepareToShow() override;
   void Show() override;
   void Hide() override;
   void OnShow() override;
   void OnHide() override;
   void OnUserAction(const std::string& action_id) override;
   void OnContextKeyUpdated(const ::login::ScreenContext::KeyType& key) override;
   void AllowGuestSignin(bool allowed) override;
   void AllowOfflineLogin(bool allowed) override;
   void FixCaptivePortal() override;
   NetworkError::UIState GetUIState() const override;
@@ skipping 73 matching lines @@
   base::CallbackList<void()> connect_request_callbacks_;
 
   base::WeakPtrFactory<ErrorScreen> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ErrorScreen);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_LOGIN_SCREENS_ERROR_SCREEN_H_