Measure input latency and text render time

[Tyriar]

WIP - This may not get merged

Part of #161622

[Tyriar]

@alexdima thoughts on the approach? Probably won't merge this for October as time is a bit tight and I'd want to see if anything goes wrong in Insiders first

[alexdima]

@Tyriar Let's look at this next debt week.

[Tyriar]

@alexdima I'll be out all next week fyi, but can meet or react to comments the first week of dev

[Tyriar]

@alexdima this is ready for a look

@lramos15 can you review the telemetry event?

[alexdima]

I like the idea. Some high level comments:

• IMHO we should move away from using the browser's performance and do the math on our won.
• We don't need a buffer, we can compute a rolling average by adding things up at each moment and dividing at the end (i.e. each data structure needs to keep min, max, avgSum and avgCount). Then there is no need to allocate memory or loop over items or worry about overflows.

[lramos15]

Telemetry side of things looks good to me 👍. Do we plan to collect this indefinitely?

[Tyriar]

@lramos15 yes

[Tyriar]

Thanks for the changes @alexdima 👍

It's done