We discussed this a bit at http://b/120770118. Although I'm not convinced this is the right solution for that specific bug, the annotation itself is really nice.

This would be a great use for ApiHelperForX classes in chromium, because the annotation is very explicit: "don't call into this class unless you're on the X API level or higher."

If we have proper support for this, I'm happy to land real changes to depend on it (the aforementioned ApiHelperForX classes).