Net: Add NET_API to the UDP code.

net/udp/datagram_client_socket.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_UDP_DATAGRAM_CLIENT_SOCKET_H_
 #define NET_UDP_DATAGRAM_CLIENT_SOCKET_H_
 #pragma once
 
 #include "net/socket/socket.h"
 #include "net/udp/datagram_socket.h"
 
 namespace net {
 
 class IPEndPoint;
 
-class DatagramClientSocket : public DatagramSocket, public Socket {
+class NET_TEST DatagramClientSocket : public DatagramSocket, public Socket {
  public:
   virtual ~DatagramClientSocket() {}
 
   // Initialize this socket as a client socket to server at |address|.
   // Returns a network error code.
   virtual int Connect(const IPEndPoint& address) = 0;
 };
 
 }  // namespace net
 
 #endif  // NET_UDP_DATAGRAM_CLIENT_SOCKET_H_