[net] Move DnsConfigService to NetworkChangeNotifier.

net/dns/dns_config_watcher.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 NET_DNS_DNS_CONFIG_WATCHER_H_
-#define NET_DNS_DNS_CONFIG_WATCHER_H_
-
-#include "base/basictypes.h"
-#include "base/memory/scoped_ptr.h"
-
-namespace net {
-namespace internal {
-
-// Watches when the system DNS settings have changed. It is used by
-// NetworkChangeNotifier to provide signals to registered DNSObservers.
-// Depending on the platform, watches files, Windows registry, or libnotify key.
-// If some watches fail, we keep the working parts, but NetworkChangeNotifier
-// will mark notifications to DNSObserver with the CHANGE_DNS_WATCH_FAILED bit.
-class DnsConfigWatcher {
- public:
-  DnsConfigWatcher();
-  ~DnsConfigWatcher();
-
-  // Starts watching system configuration for changes. The current thread must
-  // have a MessageLoopForIO. The signals will be delivered directly to
-  // the global NetworkChangeNotifier.
-  void Init();
-
-  // Must be called on the same thread as Init. Required if dtor will be called
-  // on a different thread.
-  void CleanUp();
-
- private:
-  // Platform-specific implementation.
-  class Core;
-  scoped_ptr<Core> core_;
-
-  DISALLOW_COPY_AND_ASSIGN(DnsConfigWatcher);
-};
-
-}  // namespace internal
-}  // namespace net
-
-#endif  // NET_DNS_DNS_CONFIG_WATCHER_H_