[net/dns] Isolate DnsConfigWatcher from DnsConfigService.

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;
-
 // Use DnsConfigService::CreateSystemService to use it outside of tests.
 namespace internal {
 
-class NET_EXPORT_PRIVATE DnsConfigServicePosix
-    : NON_EXPORTED_BASE(public DnsConfigService) {
+class NET_EXPORT_PRIVATE DnsConfigServicePosix : public DnsConfigService {
  public:
   DnsConfigServicePosix();
   virtual ~DnsConfigServicePosix();
 
-  virtual void Watch(const CallbackType& callback) OVERRIDE;
-
  private:
-  class ConfigWatcher;
-
-  void OnConfigChanged(bool watch_succeeded);
-  void OnHostsChanged(bool watch_succeeded);
-
-  scoped_ptr<ConfigWatcher> config_watcher_;
-  scoped_ptr<FilePathWatcherWrapper> hosts_watcher_;
+  // NetworkChangeNotifier::DNSObserver:
+  virtual void OnDNSChanged(unsigned detail) OVERRIDE;
 
   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_