SDK / exoplayer

This CL aims that the player fails upon:

- Playlist that don't change in a suspiciously long time,
  which might mean there are server side issues.
- Playlist with a media sequence lower that its last snapshot
  and no overlapping segments.

This two error conditions are propagated through the renderer,
but not through MediaSource#maybeThrowSourceInfoRefreshError.

Issue:#2872

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=160899995