Cleanup: Remove unneeded forward declararations in net.

net/base/host_resolver.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_BASE_HOST_RESOLVER_H_
 #define NET_BASE_HOST_RESOLVER_H_
 #pragma once
 
 #include <string>
 
 #include "base/memory/scoped_ptr.h"
 #include "googleurl/src/gurl.h"
 #include "net/base/address_family.h"
 #include "net/base/completion_callback.h"
 #include "net/base/host_port_pair.h"
 #include "net/base/net_export.h"
 #include "net/base/net_util.h"
 #include "net/base/request_priority.h"
 
 namespace net {
 
 class AddressList;
 class BoundNetLog;
 class HostCache;
-class HostResolverImpl;
 class HostResolverProc;
 class NetLog;
 
 // This class represents the task of resolving hostnames (or IP address
 // literal) to an AddressList object.
 //
 // HostResolver can handle multiple requests at a time, so when cancelling a
 // request the RequestHandle that was returned by Resolve() needs to be
 // given.  A simpler alternative for consumers that only have 1 outstanding
 // request at a time is to create a SingleRequestHostResolver wrapper around
@@ skipping 183 matching lines @@
     NetLog* net_log);
 
 // Creates a HostResolver implementation that sends actual DNS queries to
 // the specified DNS server and parses response and returns results.
 NET_EXPORT HostResolver* CreateAsyncHostResolver(size_t max_concurrent_resolves,
                                                  const IPAddressNumber& dns_ip,
                                                  NetLog* net_log);
 }  // namespace net
 
 #endif  // NET_BASE_HOST_RESOLVER_H_