With browser.proton.enabled set to true the gfx/layers/apz/test/mochitest/test_group_zoom-2.html test is failing on autoland. To enable proton to land this test is being forced to use the proton disabled state.

This test should be updated to work with proton. We were unable to reproduce the failures locally while trying to enable proton.

https://treeherder.mozilla.org/jobs?repo=autoland&group_state=expanded&resultStatus=usercancel%2Ctestfailed%2Cbusted%2Cexception%2Cretry&revision=1716229005d8b97f305bd663b8bc8d3fec4a4f3a&selectedTaskRun=QIY0GbcaTwas3qXnRmWpNw.0

The failing subtest is helper_click_interrupt_animation.html, and it's only failing on Mac.

What this test does is:

• Synthesizes a mouse click targeting the bottom of the vertical scrollbar track (just above the scrollbar button, if present), with the intention of triggering a smooth scroll animation.
• Synthesizes a mouse click targeting the page content, with the intention of interrupting the smooth scroll animation.
• Asserts that the animation was interrupted.

Did Proton change anything related to the behaviour or sizing of the scrollbar on Mac?

This seems to pass now. I'll enable the pref.

I think this was probably fixed by moving the task from macos 10.14 to macos 10.15. The test verify jobs still run on 10.14 and fail, the mochitest jobs run on 10.15 and pass even with many retriggers.

https://hg.mozilla.org/mozilla-central/rev/a54fdd56b10c