1470482 - Further formalize behavior of HTMLMediaElement seekToNextFrame

Status: NEW

(Core :: Audio/Video: Playback, enhancement, P3)

Description

[Bryce Seager van Dyk [:bryce] (he/him) - Not reading bugmail]

HTMLMediaElement.seekToNextFrame's internal workings have led to a number of bugs and behavior changes. seekToNextFrame is experimental, non-standard, and is used by tests, but we have not nailed down how it should behave in a number of cases.

There are some questions as to how the function should behave in various scenarios (non-exhaustive):
- If another seek is in progress should seekToNextFrame fail/succeed?
- If we allow seekToNextFrame during pending seek should we just resolve the promise when the pending seek is done, or queue up the next frame seek?

- Should we allow seekToNextFrame on elements that are not paused? (see bug 1467488 for issues caused by this)
- If we do, do we want to ensure some deterministic behavior?

It would be nice to have concrete answers to these questions and others, as to provide straight forward goals when issues are encountered with seekToNextFrame.