[net/dns] Serve requests from HOSTS file if possible.

net/dns/dns_client.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_CLIENT_H_
+#define NET_DNS_DNS_CLIENT_H_
+#pragma once
+
+#include "base/memory/scoped_ptr.h"
+#include "net/base/net_export.h"
+
+namespace net {
+
+struct DnsConfig;
+class DnsTransactionFactory;
+class NetLog;
+
+// Convenience wrapper allows easy injection of DnsTransaction into
+// HostResolverImpl.
+class NET_EXPORT DnsClient {
+ public:
+  virtual ~DnsClient() {}
+
+  // Creates a new DnsTransactionFactory according to the new |config|.
+  virtual void SetConfig(const DnsConfig& config) = 0;
+
+  // Returns NULL if the current config is not valid.
+  virtual const DnsConfig* GetConfig() const = 0;
+
+  // Could return NULL if the current config is not valid.

[mmenke, 2012/03/13 15:56:27]

Should just pick a behavior and stick with it.  Suggest you make the mock return
NULL in this case as well.

+  virtual DnsTransactionFactory* GetTransactionFactory() = 0;
+
+  // Creates default client.
+  static scoped_ptr<DnsClient> CreateClient(NetLog* net_log);
+};
+
+}  // namespace net
+
+#endif  // NET_DNS_DNS_CLIENT_H_
+