Deleted OS_WIN and all Windows specific files from base.

base/debug_message.cc

-// Copyright (c) 2006-2008 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 <windows.h>
-
-// Display the command line. This program is designed to be called from
-// another process to display assertions. Since the other process has
-// complete control of our command line, we assume that it did *not*
-// add the program name as the first parameter. This allows us to just
-// show the command line directly as the message.
-int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
-                     LPSTR lpCmdLine, int nCmdShow) {
-  LPWSTR cmdline = GetCommandLineW();
-  MessageBox(NULL, cmdline, L"Kr\x00d8m", MB_TOPMOST);
-  return 0;
-}