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

net/dns/dns_client.cc

Index: net/dns/dns_client.cc
diff --git a/net/dns/dns_client.cc b/net/dns/dns_client.cc
new file mode 100644
index 0000000000000000000000000000000000000000..5381452f9e2c2713c7cd83d797f553eb10d2eac0
--- /dev/null
+++ b/net/dns/dns_client.cc
@@ -0,0 +1,58 @@
+// 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.
+
+#include "net/dns/dns_client.h"
+
+#include "base/bind.h"
+#include "base/rand_util.h"
+#include "net/base/net_log.h"
+#include "net/dns/dns_config_service.h"
+#include "net/dns/dns_session.h"
+#include "net/dns/dns_transaction.h"
+#include "net/socket/client_socket_factory.h"
+
+namespace net {
+
+namespace {
+
+class DnsClientImpl : public DnsClient {
+ public:
+  explicit DnsClientImpl(NetLog* net_log) : net_log_(net_log) {}
+
+  virtual void SetConfig(const DnsConfig& config) OVERRIDE {
+    factory_.reset();
+    session_.release();
+    if (config.IsValid()) {
+      session_ = new DnsSession(config,
+                                ClientSocketFactory::GetDefaultFactory(),
+                                base::Bind(&base::RandInt),
+                                net_log_);
+      factory_ = DnsTransactionFactory::CreateFactory(session_);
+    }
+  }
+
+  virtual const DnsConfig* GetConfig() const OVERRIDE {
+    return session_.get() ? &session_->config() : NULL;
+  }
+
+  virtual DnsTransactionFactory* GetTransactionFactory() OVERRIDE {
+    return session_.get() ? factory_.get() : NULL;
+  }
+
+ private:
+  scoped_refptr<DnsSession> session_;
+  scoped_ptr<DnsTransactionFactory> factory_;
+
+  NetLog* net_log_;
+};
+
+}  // namespace
+
+// static
+scoped_ptr<DnsClient> DnsClient::CreateClient(NetLog* net_log) {
+  return scoped_ptr<DnsClient>(new DnsClientImpl(net_log));
+}
+
+}  // namespace net
+