I think the comment you mention makes perfect sense within the rest of its context. It's saying the rule for determining freshness is "response_is_fresh = (fres

I think the comment you mention makes perfect sense within the rest of its context. It's saying the rule for determining freshness is "response_is_fresh = (freshness_lifetime > current_age)", however that's not always the case. And looking at the code, you can see it returns true early if lifetime is equal to a new TimeDelta. The GetFreshnessLifetime function below it then covers the additional cases where it returns that. Such as the headers being set to not cache, or the expiry time being earlier than the response's time (or current time if none is provided). I think it also makes sense to assume the comment is letting us know that just because HttpResponseHeaders::RequiresValidation returns false, that doesn't mean that's the only thing that can make it require/not require a re-fetch. > There's even a line (1019) where they divide by 10 but don't explain why they do it. That's what I personally would comment. This is covered near the head of the function, line 951. Using a constant such as heuristic_scalar instead of simply using '10' would be more readable though.