See https://bugs.chromium.org/p/chromium/issues/detail?id=544723#c26

Well, technically the comment wasn't empty, but all it contained was the boilerplate text:
For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

That bug was last touched in Jan 2016, and it has an owner, so I couldn't see an obvious reason why sheriffbot poked the bug.