Make sure you run chrome with the flag --enable-extension-timeline-api

You have to enable the instrumentation as explained in the getting started doc: http://code.google.com/webtoolkit/speedtracer/get-started.ht...

I did follow the guide it just didn't do anything afterwards. Oh well.

If you have a chrome window open, or a zombie chrome process, running it again will just fork a new window from the existing browser process.

Make sure you shut them all down before running.

Works for me.