Called when the session needs to attach an audio input to the peer connection.
Called when the session needs to acquire a display input device for screen sharing.
Called when the session needs to attach a video input to the peer connection.
Add a media stream broker observer to receive events when input/output streams change
Mute the current active local audio input stream.
Remove a media stream broker observer to stop receiving events when input/output streams change
Unmute the current active local audio input
Media controllers acquire media streams from the [[MediaStreamBroker]], which fulfills the requests either through direct getUserMedia requests or a higher-level intermediary such as a [[DeviceController]].