define permission persistence

[dontcallmedom]

fixes https://www.w3.org/Bugs/Public/show_bug.cgi?id=22214
built from fluffy/webrtc-w3c#33

[adam-be]

As I understood it, the resolution about "taking away labels when all devices have been closed", refers to the MediaDeviceInfo array you get from MediaDevices.enumerateDevices() (called after all devices have been closed), not MediaStreamTrack objects. The approach so far has been to leave the informational properties on MediaStreamTrack as is even though it's ended.

[dontcallmedom]

Ah sorry, I guess I was confused; in that case, I think that pull request is probably to be scrapped then.

[adam-be]

The second part about stored permissions still applies.

Regarding taking away the label, I think we need some text in section 9.2.

From section 9.2.2:
"Collects information about the user agents available media input and output devices. The method MUST only return information that the script is authorized to access (TODO expand authorized)"

[dontcallmedom]

I've updated the pull request to reflect what I understand the rules of access to enumerateDevices() to be; please review carefully since I was obviously confused before :)

[adam-be]

Thanks for fixing this Dom.

I added a small fix that leaves resultList unmodified (since it's used again in the next invocation of the function). Instead, a copy, filteredList, is modified and emitted in the callback.