Chrome has now removed the prefixed
navigator.webkitNotifications API and as a result desktop notifications no longer work. I'm not sure exactly when this happened, but it certainly doesn't work in the latest Chrome stable ( experimental evidence indicates this change was made between v34 and 35).
window.Notification API is now active in Chrome >=22, and converting to this would also allow it to work in Firefox >=22 and Safari 6 on OSX >=10.8.
Related: Native desktop notifications
I genuinely do rate this a noticeable reduction in the general usefulness of chat, I use desktop notifications when I am at work and I would very much like them back.