Re: getThisTabMedia

1. Name - yes, we can change that. Do you have a specific alternative in
mind?
2. Audio - our intention is to mimic getDisplayMedia's behavior for
everything except the selection of source-surface. Handling of audio will
therefore be identical to when the app calls getDisplayMedia and the user
selects the current tab as the source. I am thinking (cf. PR draft
<https://github.com/eladalon1983/mediacapture-screen-share/pull/3/files>;
not yet sent) of tying the two interfaces' specifications together, so that
future changes to getDisplayMedia would apply to getThisTabMedia as well.
Including audio-related changes.