Add a SetDoNotFragment() method to DatagramSocket, and call this for

net/udp/udp_socket_win.h

Index: net/udp/udp_socket_win.h
diff --git a/net/udp/udp_socket_win.h b/net/udp/udp_socket_win.h
index 14b801e36fe4d44e3f807f3464424a95e146656f..c4ef41293d81dd76d473d61f52cb95d9cd909f7a 100644
--- a/net/udp/udp_socket_win.h
+++ b/net/udp/udp_socket_win.h
@@ -124,6 +124,13 @@ class NET_EXPORT UDPSocketWin
   // Returns a net error code.
   int SetSendBufferSize(int32_t size);
 
+  // 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
+  // code if there was a problem, but the socket will still be usable. Can not
+  // return ERR_IO_PENDING.
+  int SetDoNotFragment();
+
   // Returns true if the socket is already connected or bound.
   bool is_connected() const { return is_connected_; }