cros: Remove unused method

chrome/browser/chromeos/login/screens/base_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_BASE_SCREEN_H_
 #define CHROME_BROWSER_CHROMEOS_LOGIN_SCREENS_BASE_SCREEN_H_
 
 #include <string>
 
 #include "base/gtest_prod_util.h"
@@ skipping 15 matching lines @@
 // id.
 // Most of the screens will be re-created for each appearance with Initialize()
 // method called just once.
 class BaseScreen {
  public:
   explicit BaseScreen(BaseScreenDelegate* base_screen_delegate);
   virtual ~BaseScreen();
 
   // ---- Old implementation ----
 
-  virtual void PrepareToShow() = 0;
-
   // Makes wizard screen visible.
   virtual void Show() = 0;
 
   // Makes wizard screen invisible.
   virtual void Hide() = 0;
 
   // Returns the screen name.
   virtual std::string GetName() const = 0;
 
   // ---- New Implementation ----
@@ skipping 106 matching lines @@
   ModelViewChannel* channel_;
 
   BaseScreenDelegate* base_screen_delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(BaseScreen);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_LOGIN_SCREENS_BASE_SCREEN_H_