Support taking pictures automatically

All of the code seems to be directed at the use case of "send user to Camera app intent, let them take a picture, get the results"

Which is great, unless you want to do something automatic, like taking a picture on a timer, or taking a picture every second to create a time-lapse, etc. 

Proposed: A new API call that lets the camera's parameters (focus, exposure etc) stabilize and immediately snaps the pic and returns.

The example at https://developer.mozilla.org/en-US/docs/Web/API/WebRTC_API/Taking_still_photos looks like it is taking a frame from the Video feed, which is lower res, ideal would be a full-still-res photo.