Filed by: rmaries [at] mozilla.com
Parsed log: https://treeherder.mozilla.org/logviewer.html#?job_id=293111621&repo=autoland
Full log: https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/eivkDbujSDu44G_So9XLtQ/runs/0/artifacts/public/logs/live_backing.log

[task 2020-03-13T22:10:59.280Z] 22:10:59 INFO - TEST-START | gfx/layers/apz/test/mochitest/test_group_hittest.html
[task 2020-03-13T22:11:20.471Z] 22:11:20 INFO - GECKO(2956) | #36 main /builds/worker/checkouts/gecko/browser/app/nsBrowserApp.cpp:303:18 (firefox+0xc86c7)
[task 2020-03-13T22:11:20.472Z] 22:11:20 INFO - GECKO(2956) | SUMMARY: ThreadSanitizer: data race /builds/worker/checkouts/gecko/gfx/skia/skia/include/core/SkTypes.h:87:80 in SkToBool<bool>
[task 2020-03-13T22:11:20.473Z] 22:11:20 INFO - GECKO(2956) | ==================
[task 2020-03-13T22:11:20.473Z] 22:11:20 INFO - GECKO(2956) | ###!!! [Parent][MessageChannel] Error: (msgtype=0x37012E,name=PContent::Msg_DetachBrowsingContext) Channel error: cannot send/recv
[task 2020-03-13T22:11:20.953Z] 22:11:20 ERROR - GECKO(2956) | A content process crashed and MOZ_CRASHREPORTER_SHUTDOWN is set, shutting down
[task 2020-03-13T22:11:32.258Z] 22:11:32 INFO - GECKO(2956) | 1584137492253 Marionette TRACE Received observer notification xpcom-will-shutdown
[task 2020-03-13T22:11:32.259Z] 22:11:32 INFO - GECKO(2956) | 1584137492254 Marionette INFO Stopped listening on port 2828
[task 2020-03-13T22:11:32.259Z] 22:11:32 INFO - GECKO(2956) | 1584137492255 Marionette DEBUG Marionette stopped listening

(I'm moving these to Graphics because even though it's an APZ test that's triggering the race, the race is in Skia code, e.g. DrawTargetSkia::Fill() and PathSkia::ContainsPoint().)

Kats, could you please look over this one too? https://treeherder.mozilla.org/#/jobs?repo=autoland&tochange=026b396d278821202955c5a422723c09df428e54&searchStr=d0fa0fec45447d5677895e4ebf8536dc522e875d&group_state=expanded&fromchange=9a15759c605aebdda20d5c5a1fa514d5e7a4580e&selectedJob=293226902
It also shows up frequently on beta-sims. Thanks.

I'll take a look

Investigation will happen over in bug 1622445 since they seem to be very similar.

Fixed via bug 1622445.