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

net/udp/udp_client_socket.cc

Index: net/udp/udp_client_socket.cc
diff --git a/net/udp/udp_client_socket.cc b/net/udp/udp_client_socket.cc
index 7c3a2722a17de6445d222899d3d413e04419beaa..2723b4ee4755f43b5883dfe034ccda81098b53ba 100644
--- a/net/udp/udp_client_socket.cc
+++ b/net/udp/udp_client_socket.cc
@@ -109,6 +109,10 @@ int UDPClientSocket::SetSendBufferSize(int32_t size) {
   return socket_.SetSendBufferSize(size);
 }
 
+int UDPClientSocket::SetDoNotFragment() {
+  return socket_.SetDoNotFragment();
+}
+
 const BoundNetLog& UDPClientSocket::NetLog() const {
   return socket_.NetLog();
 }