Remove some illegal enum forward declarations

sandbox/win/sandbox_poc/main_ui_window.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 SANDBOX_SANDBOX_POC_MAIN_UI_WINDOW_H__
 #define SANDBOX_SANDBOX_POC_MAIN_UI_WINDOW_H__
 
 #include <windows.h>
 
 #include <string>
 
 #include "base/macros.h"
 #include "base/strings/string16.h"
 
 namespace sandbox {
 class BrokerServices;
-enum ResultCode;
 }
 
 // Header file for the MainUIWindow, a simple window with a menu bar that
 // can pop up a dialog (accessible through the menu bar), to specify a path and
 // filename of any DLL to load and choose an entry point of their choice
 // (note: only entry points with no parameters are expected to work).
 //
 // The purpose of this is to be able to spawn an EXE inside a SandBox, have it
 // load a DLL and call the entry point on it to test how it behaves inside the
 // sandbox. This is useful for developer debugging and for security testing.
@@ skipping 159 matching lines @@
   // user.
   static HWND list_view_;
 
   // Pipe used to communicate the logs between the target and the broker.
   HANDLE pipe_handle_;
 
   DISALLOW_COPY_AND_ASSIGN(MainUIWindow);
 };
 
 #endif  // SANDBOX_SANDBOX_POC_MAIN_UI_WINDOW_H__