Right now, they're set statically on shell creation when the engine is started or a new one is spawned. However, this will not be correct for systems that scale the refresh rate dynamically. Something like what's being done for #93688 would be helpful here, perhaps with some kind of refactor to make the vsync waiter implementation and the shell use the same API surface to get this information.

@iskakaushik knows more about this. AFAIK this only affects timing reports, and does not actually impact how submit things fo rrendering.