Chrome (45) won't connect to websocket server due to "Sec-WebSocket-Protocol" missing from response

The latest version of Chrome was refusing to connect to the web socket server.
I tracked this down to and issue with the header being returned by the service.
Chrome rejects the connection if no web socket protocol value is returned back to the client in the headers. I did not see anyway without modifying the code to make this happen.

My temporary workaround to the issue was to change the HttpServer class in the "receiveRequest" method. The following code below was the issue.
if (ctx.Request.IsUpgradeTo ("websocket")) {
processRequest (ctx.AcceptWebSocket (null));
return;
}

I had to replace the "null" with a string for the protocol name that I wanted to socket to return when it sent back the headers to the connecting client. After making that change Chrome will now successfully connect to the web socket server.
PS: I also had to set the "IgnoreExtensions" property as mentioned in other posts to avoid issues with the compression.

Ideally the WebSocketBehavior class would provide a method that would allow you to "Negotiate" what protocol value to return when the connection is being established.

Start in the HttpServer receiveRequest method described in the issue and trace how AcceptWebSocket(null) constructs the response headers. Then inspect WebSocketBehavior for the proposed negotiation entry point and verify the connection behavior with Chrome, including the IgnoreExtensions setting; done means the negotiated Sec-WebSocket-Protocol is returned without breaking existing WebSocket connections.