- Fix bug where we'd try and call replaceStream having already
notified the renderer that the current stream is final. This
could occur if a period was added to the end of the playlist.
- If the current period being played is removed and a new period
to play cannot be resolved, assume we've gone off the end of
the playlist and transition to the ended state. This allows
the current source to be re-used (unlike the previous behavior
of considering it an error). Treat valid seeks that cannot be
resolved due to concurrent timeline update similarly.
- Add seek sanity check back to ExoPlayerImpl. Meh. It's probably
best to keep this, since it stops the exposed window index
being invalid w.r.t the exposed timeline.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=141167151
