Following  issue 883321 , Mac trybots (including CQ bots & Blink trybots) will retry without and with the patch in case of failures, but they do not archive the retry summary as other bots.

Example: https://ci.chromium.org/p/chromium/builders/luci.chromium.try/mac10.13-blink-rel/2366
Compare it with a Linux job: https://ci.chromium.org/p/chromium/builders/luci.chromium.try/linux-blink-rel/3748
(search for archive_retry_summary)

I suspect this is because of the GPU suffix in the step name on Mac bots (e.g. "webkit_layout_tests on Intel GPU on Mac (with patch)"), so this condition might need to be changed to `test_name.startswith` instead of `==`:
https://cs.chromium.org/chromium/build/scripts/slave/recipe_modules/test_utils/api.py?l=265&rcl=a98e66b1a581a3e9d4c2d0b569de517d81e52489

Yet I'm unfamiliar with the recipes and don't know how to properly test this.