Before this change:
* With legacy subtitle decoding (at render time), load errors (e.g. HTTP
404) would result playback completely failing, while parse errors
(e.g. invalid WebVTT data) would be silently ignored, so playback
would continue without subtitles.
* With new subtitle decoding (at extraction time), both load and parse
errors would result in playback completely failing.
This change means that now neither load nor parse errors in text or
metadata tracks stop playback from continuing. Instead the error'd track
is disabled until the end of the current period.
With new subtitle decoding, both load and parse errors happen during
loading/extraction, and so are emitted to the app via
`MediaSourceEventListener.onLoadError` and
`AnalyticsListener.onLoadError`. With legacy subtitle decoding, only
load errors are emitted via these listeners and parsing errors continue
to be silently ignored.
Issue: androidx/media#1722
PiperOrigin-RevId: 686902979
49dec5db8b