Headers to indicate that websocket server doesn't support any extensions
===

We've got a problem with Chrome 19 websockets. It is attempting to connect to our server using  the `x-webkit-deflate-frame` extension. However, I can't work out how to indicate to that client that we don't support that extension (or if it's a Chrome 19 bug and is just ignoring the fact that we don't support it?). I have seen this problem related in a few SO answers but I can't see a consistent solution.

For example, if we receive the headers

    Upgrade: websocket
    Connection: Upgrade
    Host: titantest:30100
    Origin: http://titantest
    Sec-WebSocket-Key: f+7h4rrKKqdRRdD7WwTZow==
    Sec-WebSocket-Version: 13
    Sec-WebSocket-Extensions: x-webkit-deflate-frame

What should we respond with?

    HTTP/1.1 101 Switching Protocols
    Upgrade: websocket
    Connection: Upgrade
    Sec-WebSocket-Accept: 3eazAhsFLXFWB1OjcYMtzP13yag=

and then appended to that I've tried various `Sec-WebSocket-Extension` varieties

    Sec-WebSocket-Extension: '-'
    Sec-WebSocket-Extension: -
    Sec-WebSocket-Extension: 
    <- blank: don't send a Sec-WebSocket-Extension header ->

I've also got a copy of the websocket protocol in front of me, so feel free to point out what I've missed/misread.