Revert 85646 - Adds support for the DHCP portion of the WPAD (proxy auto-discovery) protocol.

net/proxy/dhcpcsvc_init_win.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 NET_PROXY_DHCPCSVC_INIT_WIN_H
-#define NET_PROXY_DHCPCSVC_INIT_WIN_H
-#pragma once
-
-namespace net {
-
-// Initialization of the Dhcpcsvc library must happen before any of its
-// calls are made.  This function will make sure that the appropriate
-// initialization has been done, and that uninitialization is also
-// performed at static uninitialization time.
-//
-// Note: This initializes only for DHCP, not DHCPv6.
-void EnsureDhcpcsvcInit();
-
-}  // namespace net
-
-#endif  // NET_PROXY_DHCPCSVC_INIT_WIN_H