Expose the Media elements and AudioContext participating in the MediaSession

[mounirlamouri]

This is mostly to keep track of the idea. I don't think we should work on that soon because it can be added later.

It might be easier for developers if the session were to expose the media session participants because the UA must know them. The current API would require web pages to keep track of these in parallel.

[richtr]

I agree this may be good and it could be added later. Let's leave this issue open for now pending further implementer feedback/interest?

We will also need to decide if ordering is important (related: https://bugs.webkit.org/show_bug.cgi?id=146421) and how to maintain object references when active audio-producing objects are removed from the list(s).

[xxyzzzq]

Closing this issue since we are moving audio focus out to a separate API.

[xxyzzzq]

This issue was moved to WICG/audio-focus#21