Comment 9 for bug 1498466

FWIW, Android apparently has exactly the same issue: volume buttons control the active audio stream if there is one, and the ringer if there isn’t, which is awkward if an app frequently plays sound but isn’t right now. Their solution is for those kinds of app to call a “setVolumeControlStream()” function when they launch. <https://developer.android.com/training/managing-audio/volume-playback.html> I guess the benefit is that they keep the distinct roles; the drawback is that different apps, maybe unexpectedly, behave in different ways.