The timer histograms for the cases where we are in a worker are implemented using static variables.  When running with assertions enabled, this causes crashes due to thread safety checks. This can be observed when re-loading a page that uses offscreencanvas.commit in a worker. After reloading the page, a new worker is created and the statics end up being accessed on a different thread from where they were initialized.  This is most likely also causing flake on the test bots: If two offscreen canvas "in-worker" tests get executed on the same test driver, the second test will crash.