STR:

1. Open DevTools Toolbox, select the Debugger panel
2. Load this page: http://janodvarko.cz/tests/debugger/service-workers/
3. Click Register Worker in test case #1
4. Create BP in service-worker.js on line 33 console.log("install", event)
5. Click Unregister Worker in test case #1
6. Click Register Worker in test case #1
7. The debugger pauses on line 33, but the BP isn't displayed (the blue marker isn't there)

Honza

The problem here is related to how we treat service worker sources separately from one another, so that we can have multiple tabs with different versions of the source for different workers. When we unregister and re-register the service worker, the debugger client has a new source, and the pending breakpoints logic has some logic that prevents the breakpoint from being applied to the new service worker source. This logic is pretty weird and I tried removing it in bug 1534786, but it caused jest failures so I left it alone. Those jest failures don't seem to be happening anymore so hopefully we can just simplify the pending breakpoints logic and fix this bug in the meantime.

https://hg.mozilla.org/mozilla-central/rev/4ffb6c6fcbc0