Always use NonBlocking IO for UDP sockets on Windows.

media/cast/net/udp_transport.h

 // Copyright 2014 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 MEDIA_CAST_NET_UDP_TRANSPORT_H_
 #define MEDIA_CAST_NET_UDP_TRANSPORT_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 49 matching lines @@
   void SetDscp(net::DiffServCodePoint dscp);
 
   // Set UdpTransport options.
   // Possible keys are:
   //   "pacer_max_burst_size": int
   //        - Specifies how many pakcets to send per 10 ms, maximum.
   //   "send_buffer_min_size": int
   //        - Specifies the minimum socket send buffer size.
   //   "DSCP" (value ignored)
   //       - Turns DSCP on (higher IP Precedence and Type of Service).
-  //   "disable_non_blocking_io" (value ignored)
-  //       - Windows only.  Turns off non-blocking IO for the socket.
-  //         Note: Non-blocking IO is, by default, enabled on all platforms.
   void SetUdpOptions(const base::DictionaryValue& options);
 
   // This has to be called before |StartReceiving()| to change the
   // |send_buffer_size_|. Calling |SetUdpOptions()| will automatically call it.
   void SetSendBufferSize(int32_t send_buffer_size);
 
-#if defined(OS_WIN)
-  // Switch to use non-blocking IO. Must be called before StartReceiving().
-  void UseNonBlockingIO();
-#endif
-
   // PacketTransport implementations.
   bool SendPacket(PacketRef packet, const base::Closure& cb) final;
   int64_t GetBytesSent() final;
 
  private:
   // Requests and processes packets from |udp_socket_|.  This method is called
   // once with |length_or_status| set to net::ERR_IO_PENDING to start receiving
   // packets.  Thereafter, it is called with some other value as the callback
   // response from UdpSocket::RecvFrom().
   void ReceiveNextPacket(int length_or_status);
@@ skipping 25 matching lines @@
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<UdpTransport> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(UdpTransport);
 };
 
 }  // namespace cast
 }  // namespace media
 
 #endif  // MEDIA_CAST_NET_UDP_TRANSPORT_H_