In  issue 828031  we were experiencing regular and frequent bot deaths when running browser_tests. We've stopped that from occurring by placing lots of tests on a gtest filter https://cs.chromium.org/chromium/src/testing/buildbot/filters/mac_window_server_killers.browser_tests.filter?rcl=d710e152dcde637694e68c346b403d775276a98e

Some of those tests are responsible for causing the WindowServer to crash, which then puts the bot into a DEAD state. But other tests were added in bulk and probably have nothing to do with the crashes.

I've tried running each disabled test in isolation on swarming with a high gtest_repeat, but that didn't suss out any culprits at all. Instead, we're going to have to slowly remove tests from the filter while verifying that the fleet stays healthy.