DR-251. Scrubbing was dead on Android because the seek bar had no scale:
every position tick read `<position> / 0.0`.
ExoPlayer reports C.TIME_UNSET until it has resolved a duration, and
JellyTauPlayer.getDuration() maps that to 0.0. So the engine answered
Some(0.0) rather than None, which satisfied every "unknown duration" fallback
in the controller — `observed_duration()` was never consulted, and neither was
the runtime the catalog had carried since long before anything started
decoding.
Zero is now read as "does not know yet" at each step, with a final fallback to
the item's own duration. That fixes it for any engine that cannot answer,
rather than for ExoPlayer specifically.
Red first: the test asserts a controller whose engine reports nothing usable
still reports the queued item's 1800s, and failed with None before the change.
790 Rust tests, clippy clean both ways.
dtourolle
e5b7003489