Always use NonBlocking IO for UDP sockets on Windows.

net/socket/datagram_socket.h

Index: net/socket/datagram_socket.h
diff --git a/net/socket/datagram_socket.h b/net/socket/datagram_socket.h
index f5294745cc32c12918422c619d5eadbb7cf97056..0e973537b1d52dba62ac883dcc50d91882685f78 100644
--- a/net/socket/datagram_socket.h
+++ b/net/socket/datagram_socket.h
@@ -34,10 +34,6 @@ class NET_EXPORT_PRIVATE DatagramSocket {
   // (similar to getsockname)
   virtual int GetLocalAddress(IPEndPoint* address) const = 0;
 
-  // Switch to use non-blocking IO. Must be called right after construction and
-  // before other calls.
-  virtual void UseNonBlockingIO() = 0;
-
   // Requests that packets sent by this socket not be fragment, either locally
   // by the host, or by routers (via the DF bit in the IPv4 packet header).
   // May not be supported by all platforms. Returns a return a network error