net: Cleanup class/struct forward declarations

net/dns/dns_config_service.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_H_
 #define NET_DNS_DNS_CONFIG_SERVICE_H_
 
 #include <map>
 #include <memory>
 #include <string>
@@ skipping 10 matching lines @@
 #include "net/base/ip_endpoint.h"  // win requires size of IPEndPoint
 #include "net/base/net_export.h"
 #include "net/dns/dns_hosts.h"
 
 namespace base {
 class Value;
 }
 
 namespace net {
 
-class IPAddress;
-
 // Default to 1 second timeout (before exponential backoff).
 const int64_t kDnsDefaultTimeoutMs = 1000;
 
 // DnsConfig stores configuration of the system resolver.
 struct NET_EXPORT_PRIVATE DnsConfig {
   DnsConfig();
   DnsConfig(const DnsConfig& other);
   virtual ~DnsConfig();
 
   bool Equals(const DnsConfig& d) const;
@@ skipping 132 matching lines @@
 
   // Started in Invalidate*, cleared in On*Read.
   base::OneShotTimer timer_;
 
   DISALLOW_COPY_AND_ASSIGN(DnsConfigService);
 };
 
 }  // namespace net
 
 #endif  // NET_DNS_DNS_CONFIG_SERVICE_H_