This is apparently caused by something not in Chromium itself: it’s not reproducible in a VM running Oneiric, with 17.0.963.26 from ppa:chromium-daily/dev nor with Chrome 17.0.96356. It *is* reproducible in Precise with the latter too, but not reproducible with Firefox nor Epiphany. In Precise with Chromium 17, it’s reproducible with a temporary profile and a guest login also.