- Use a single constant for unset/unknown times across
all time bases. Note also that this moves away from
use of -1 for unset/unknown times in ms, which was a
bad choice (it might conflict with real times, such
as a time representing being just behind the start
of a live window).
- Add a few other unset constants, and use them.
- Fix some hardcoding of -1 where existing constants
should have been used.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=130775594
1579b68cf6