AudioTrack automatically ramps down volume when pausing. However,
when this happens as part of a AudioSink.flush() operation, we
need to postpone the actual flush() until the ramp down finished
in the audio system. Otherwise audio is just cut off, creating pop
sounds.
Delaying the release is fine now, because DefaultAudioSink starts
creating a new track immediately without waiting for the previous
track to be released.
Also using the opportunity to add more comments about related quirks
of the AudioTrack flush/release handling for more context.
PiperOrigin-RevId: 654794818
6147050b90