This is a meta bug to track all media control related issues and there are some different possible features which we could implement under this topic.
1. Support hardware media keys
No matter play/pause keys from normal keyboard, from Mac's touch bar, or from the headphone or any other hardware controllers which are desinated to control media, we should provide an ability to control media via these keys.
2. Media Control Interface on desktop
Chrome has implemented something like that , which is a controller interface to play/pause/seek next or prev (if website implements that via MediaSession).
When websites implements MediaSession, they would hook up the control to that session object. If they doesn't, controller can still control media via a default session object.
Although we haven't had any implementation for MediaSession yet, we can still acheieve this feature by the implementation in bug1565689.
3. An external Media Control Module for GeckoView
We have a media control interface on Fennec, which will show in Android notification bar and lockscreen while media is playing, but we have nothing on Fennix.
So we could implement some API to let GeckoView create an extern module which are used to control media inside Gecko.