[net/dns] Watch configd notifications to detect DnsConfig changes on Mac.

net/dns/dns_config_service_posix.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_SERVICE_POSIX_H_
 #define NET_DNS_DNS_CONFIG_SERVICE_POSIX_H_
 #pragma once
 
 #include <sys/types.h>
 #include <netinet/in.h>
 #include <resolv.h>
 
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 #include "net/base/net_export.h"
 #include "net/dns/dns_config_service.h"
 
 namespace net {
 
 class FilePathWatcherWrapper;
+class NotifyWatcherMac;
 
 // Use DnsConfigService::CreateSystemService to use it outside of tests.
 namespace internal {
 
 class NET_EXPORT_PRIVATE DnsConfigServicePosix
     : NON_EXPORTED_BASE(public DnsConfigService) {
  public:
   DnsConfigServicePosix();
   virtual ~DnsConfigServicePosix();
 
   virtual void Watch(const CallbackType& callback) OVERRIDE;
 
  private:
   void OnConfigChanged(bool watch_succeeded);
   void OnHostsChanged(bool watch_succeeded);
 
   scoped_ptr<FilePathWatcherWrapper> config_watcher_;
   scoped_ptr<FilePathWatcherWrapper> hosts_watcher_;
+#if defined(OS_MACOSX)
+  scoped_ptr<NotifyWatcherMac> notify_watcher_;
+#endif
 
   scoped_refptr<SerialWorker> config_reader_;
   scoped_refptr<SerialWorker> hosts_reader_;
 
   DISALLOW_COPY_AND_ASSIGN(DnsConfigServicePosix);
 };
 
 // Fills in |dns_config| from |res|.
 bool NET_EXPORT_PRIVATE ConvertResStateToDnsConfig(
     const struct __res_state& res, DnsConfig* dns_config);
 
 }  // namespace internal
 
 }  // namespace net
 
 #endif  // NET_DNS_DNS_CONFIG_SERVICE_POSIX_H_