Max, I think we'll put this on your backlog.
It's lower priority than the rest of your work currently.

I am looking at https://github.com/w3c/performance-timeline/pull/76
The WebIdl looks like this: 

dictionary PerformanceObserverInit {
  required sequence<DOMString> entryTypes;
  boolean buffered = false;
};

But it's not in PerformanceObserverInit yet. https://cs.chromium.org/chromium/src/out/Debug/gen/blink/core/timing/PerformanceObserverInit.h?dr=CSs

So the scope of this issue includes creating a 'buffered' flag according to the spec? And the issue 718486 (https://bugs.chromium.org/p/chromium/issues/detail?id=718486) is based on this issue, is it right? 

Yup, your interpretation sounds correct to me.

Feel free to block that bug on this one.

I am not clear about the roadmap of this issue. There doesn't seem to be specs or tests around the buffered flag for paint and longtasks in https://w3c.github.io/performance-timeline yet. 

I don't think the relation between the buffered flag and specific entry types needs to be specified. The spec for "buffered":

> Let entries be the PerformanceEntryList object returned by the 4.2 Filter 
> buffer by name and type algorithm with buffer set to performance entry 
> buffer, name set to null and type set to entryType.

That implicitly applies to all entryTypes.

Sorry I misread this issue. My focus was on long-task and paint. Actually the focus of this issue should be to support the behavior of the buffered flag in general. And the longtask part should instead be solved in Issue 718486. 

Update: already scheduled to work on it in this quarter.

The title of this bug mentions longtasks, which makes me wonder: will we actually observe previous longtasks with the buffered flag? I think these are not added to the performance buffer, so if we want the buffered flag to work for longtasks then we need to modify the spec.

Yeah, we do want this to work for longtasks.

Hey Max: any update on this bug? Looks like it's been in progress since Q2, but isn't done yet.

Haven't worked on this for a while after it get de-prioritized.

There was an WIP CL (https://chromium-review.googlesource.com/c/chromium/src/+/641382) but I believe a lot has changed. Will restart the task at some point. But for now I will move it back to assigned.