Allow apps to preload the first period of the next window in
the playlist of `ExoPlayer`. By default playlist preloading is
disabled. To enable preloading,
`ExoPlayer.setPreloadConfiguration(PreloadConfiguration)` can be
called.
`LoadControl` determines when to preload with its implemenation of `shouldContinuePreloading(timeline, mediaPeriodId, bufferedDurationUs)`.
The implementation in `DefaultLoadControl` allows preloading only when
the player isn't currently loading for playback. Apps can override this
behaviour.
Issue: androidx/media#468
PiperOrigin-RevId: 677786017
ba1cdba403