We know of some cases where a user's profile is quite large, resulting in poor performance of the system. I think we should get some more metrics to see how much of a problem this is.

1) Look through Chrome to see what existing UMA metrics we have for profile-related stats. There are some specialized UMA metrics [e.g. bookmarks, cookies, etc.].

2) Add an UMA metric for disk-usage of the profile. I'm pretty sure this doesn't exist. I expect some truly horrifying numbers. Depending on how fast this is, we should run it either every UMA upload period [e.g. 15min on mobile, 30min on desktop] or much less often [e.g. every 24 hours].

3) Find a way to get thorough UMA metrics for memory usage of the profile loaded into memory. Ideally in a way that's more efficient/comprehensive than just trying to find every subsystem that uses the profile [of which there are many] and logging stats for them.

I would say that (2) is a Pri-2 feature request, and (3) is a Pri-3 feature request.