Rather than write new tests specific to using the service worker background, we want to have a configuration ini file that will cause loadExtension to switch background pages to the service worker. We can cherry pick the tests that we will add into that ini file.

Provide a way to use service workers as the background script in existing tests.

This patch includes:

• a new xpcshell-serviceworker.ini manifest, all tests included in this manifest will also run in the
  "background service worker mode", initially including all alarms API xpcshell tests

• some small changes to test_ext_alarms.js to temporarily skip test case that can't yet pass
  while running in "background service worker mode" (until fixed in separate followups)

• some small tweaks to head_service_worker.js to avoid failure due to an existing ExtensionCommon
  const bindings being redefined while running a test for the xpcshell-remote.ini manifest

Depends on D122536

Backed out for causing python failures

Backout link: https://hg.mozilla.org/integration/autoland/rev/f1bf4a027490d20440a1cea3f86e397bdcfa1327

Push with failures: https://treeherder.mozilla.org/jobs?repo=autoland&selectedTaskRun=S51u_yLqQ7eMo5l2-6jKbg.0&resultStatus=testfailed%2Cbusted%2Cexception%2Cretry%2Cusercancel&revision=461db77b2f1f5e95ba7b52b98cb563b084bc9b26

Failure log(s): https://treeherder.mozilla.org/logviewer?job_id=363758551&repo=autoland

(In reply to Norisz Fay [:noriszfay] from comment #6)

Backed out for causing python failures

Backout link: https://hg.mozilla.org/integration/autoland/rev/f1bf4a027490d20440a1cea3f86e397bdcfa1327

Push with failures: https://treeherder.mozilla.org/jobs?repo=autoland&selectedTaskRun=S51u_yLqQ7eMo5l2-6jKbg.0&resultStatus=testfailed%2Cbusted%2Cexception%2Cretry%2Cusercancel&revision=461db77b2f1f5e95ba7b52b98cb563b084bc9b26

Failure log(s): https://treeherder.mozilla.org/logviewer?job_id=363758551&repo=autoland

I see what is triggering that python test failure, and I was also able to reproduce it locally (unfortunately that python test was not part of the same set of tests I added a new test case to, and so it did not run in my push to try).

I've updated https://phabricator.services.mozilla.com/D134293 with a small trivial change that fix the failure, and I'll push it to autoland again in a few minutes.

https://hg.mozilla.org/mozilla-central/rev/a78cf95d81c9
https://hg.mozilla.org/mozilla-central/rev/439ad9645e72
https://hg.mozilla.org/mozilla-central/rev/0c06f0e7e4a2