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

net/socket/socks5_client_socket.cc

Index: net/socket/socks5_client_socket.cc
diff --git a/net/socket/socks5_client_socket.cc b/net/socket/socks5_client_socket.cc
index ae362ceb4ce0e70ee243813639d88a669b440894..13eaf92d221bab37d4ff2d878a3eb12f3775e640 100644
--- a/net/socket/socks5_client_socket.cc
+++ b/net/socket/socks5_client_socket.cc
@@ -189,6 +189,10 @@ int SOCKS5ClientSocket::SetSendBufferSize(int32_t size) {
   return transport_->socket()->SetSendBufferSize(size);
 }
 
+int SOCKS5ClientSocket::SetDoNotFragment(bool do_not_fragment) {
+  return transport_->socket()->SetDoNotFragment(do_not_fragment);
+}
+
 void SOCKS5ClientSocket::DoCallback(int result) {
   DCHECK_NE(ERR_IO_PENDING, result);
   DCHECK(!user_callback_.is_null());