Chrome traces of ServiceWorker thread activity can be ambiguous since there is no information to indicate which site a running S/W thread belongs to.

I am posting a patch that records the script URLs of running ServiceWorkers as a metadata tracing event. If this approach looks good, I'll submit a separate patch to the catapult project to surface this new info in chrome://tracing.

FYI this is my first Chrome patch, so I suspect I've gotten a few things wrong :)
You'll find my organization's name (Facebook) in the AUTHORS file.