(private) implementation_ :shaka.media.StallDetector.Implementation
(private) stallThresholdSeconds_ :number
The amount of time in seconds that we must have the same value of |value_| before we declare it as a stall.
Set the callback that should be called when a stall is detected. Calling this will override any previous calls to |onStall|.
Have the detector update itself and fire the "on stall" callback if a stall was detected.