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

net/spdy/spdy_proxy_client_socket.cc

Index: net/spdy/spdy_proxy_client_socket.cc
diff --git a/net/spdy/spdy_proxy_client_socket.cc b/net/spdy/spdy_proxy_client_socket.cc
index d33f59ac67f363afd562f88693d485dc8a0956f7..4e980df518e8a15c0296c34360bffbcd68a79f83 100644
--- a/net/spdy/spdy_proxy_client_socket.cc
+++ b/net/spdy/spdy_proxy_client_socket.cc
@@ -252,6 +252,12 @@ int SpdyProxyClientSocket::SetSendBufferSize(int32_t size) {
   return ERR_NOT_IMPLEMENTED;
 }
 
+int SpdyProxyClientSocket::SetDoNotFragment(bool do_not_fragment) {
+  // Since this StreamSocket sits on top of a shared SpdySession, it
+  // is not safe for callers to change this underlying socket.
+  return ERR_NOT_IMPLEMENTED;
+}
+
 int SpdyProxyClientSocket::GetPeerAddress(IPEndPoint* address) const {
   if (!IsConnected())
     return ERR_SOCKET_NOT_CONNECTED;