Actually, https://cs.chromium.org/chromium/src/chrome/test/data/extensions/api_test/tab_capture/fullscreen_test.js does not use the webkitfullscreenchange event, so if the flakiness was caused by my change, it was because of changes in when document.webkitFullscreenElement changes.

However, per issue 675851 the test was already flaky and is now in fact disabled entirely.

I've tried enabling the test on top of https://codereview.chromium.org/2855843002/ and ran the test 100 times with no flakiness. However, I'll do nothing further since the test is disabled.