MediaStreamTrack transfer requires secure context?

[dogben]

Many APIs providing a MediaStreamTrack are limited by SecureContext in WebIDL, such as enumerateDevices, getUserMedia, and getDisplayMedia. Other APIs do not require a SecureContext, e.g. captureStream.

Which of the following is the correct restriction for transferring a MediaStreamTrack?

1. Any track can be transferred, regardless of whether the origin and/or destination contexts are secure. (This is how I interpret the current wording.)
2. Transfer fails if either the origin or destination contexts are not secure.
3. If the origin context is secure, transfer fails if the destination context is not secure.
4. Something else?

@alvestrand