We currently try to keep track of the playback queue (MediaPeriodQueue)
by listening to onMediaPeriodCreated/onMediaPeriodReleased events.
This approach has some problems:
1. It's easily broken by custom MediaSources that don't report these
events correctly.
2. We need to make some assumptions about what the order of these
events actually means. For example it is currently important that
the playing period gets released last in MediaPeriodQueue.clear()
3. We don't see batched events (like MediaPeriodQueue.clear()), so that
it is impossible to keep the "last reading period" for example. This
information is needed to correctly associate renderer errors to
periods after the queue has been cleared.
All of these problems can be solved by directly tracking the queue.
This also makes the onMediaPeriodCreated/Released/ReadingStarted events
obsolete and they can be removed in a future change.
PiperOrigin-RevId: 319739993
27c239d6b3