Always use NonBlocking IO for UDP sockets on Windows.

media/cast/net/udp_transport.h

Index: media/cast/net/udp_transport.h
diff --git a/media/cast/net/udp_transport.h b/media/cast/net/udp_transport.h
index eceb349ab4eda90c92309fb0381fca1b9ce2bad4..ad9a988a280401dc697515239bb2900aede6d120 100644
--- a/media/cast/net/udp_transport.h
+++ b/media/cast/net/udp_transport.h
@@ -67,20 +67,12 @@ class UdpTransport : public PacketTransport {
   //        - 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;