Chrome Version: ToT as of today
OS: Linux, but should affect all

What steps will reproduce the problem?
(1) Build Chrome and fake missing callbacks to trigger local track to be stopped, e.g. by using https://codereview.chromium.org/2891303002/ for Linux.
(2) Do a call with https://appr.tc/?debug=loopback.
(3) Open chrome://webrtc-internals in a new tab, expand stats graphs for send audio.
(4) Make sure to make some sound constantly in the mic so that audioInputLevel goes up a bit.

What is the expected result?
When audio stops being audible, the audioInputLevel should be 0.

What happens instead?
audioInputLevel is stuck at the last level.