short descriptions of arguments to callbacks in callback-based gUM

[dontcallmedom]

No description provided.

[alvestrand]

Looks good to me.

[burnburn]

These should refer to navigator.getUserMedia() rather than navigator.mediaDevices.getUserMedia() since these are only applicable to the callback version of the API. Otherwise, thanks for filling these in :)

[dontcallmedom]

@burnburn I've used mediaDevices references on purpose — that's where the algorithms are defined nowadays.

[alvestrand]

After talking to Dan, I think he's right. We need to point to navigator.getUserMedia for the procedure, because that's where we define what the argument for the callback is - the mediaDevices.getUserMedia definition talks about resolving a promise.

[dontcallmedom]

ok, will update