https://chromium-review.googlesource.com/c/chromium/src/+/732813 seems a trigger.

I don't think this was caused by my CL. It looks like majidvp's CL to rename scroll-boundary-behavior also got reverted speculatively for this issue (https://chromium-review.googlesource.com/c/chromium/src/+/738295)

On mac, the build went green after picking up the revert of that, but it had not yet picked up the revert of https://chromium-review.googlesource.com/c/chromium/src/+/737693 (in https://chromium-review.googlesource.com/c/chromium/src/+/738335)

Contains revert of renaming scroll-boundary-behavior:
https://build.chromium.org/p/chromium/builders/Mac/builds/34061

Revert of generator refactor picked up in
https://build.chromium.org/p/chromium/builders/Mac/builds/34062

Majid, I had a quick look at your CL but nothing stood out at me as possibly causing this issue. Could you PTAL?

Yes my patch did have a mistake in BUILD file that was causing noop build to fail. It go reverted and I have already relanded the patch with a fix.
The builders are green now.