olly b15ceba780 Enhance DefaultTrackSelector part 2
- Support specifying a preferred text language.
- Score based selection for text/audio/other tracks.
- Prefer default tracks to non-default ones.
- Allow overriding of base select*Track methods.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=129626994
2016-08-10 20:05:31 +01:00
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2016-08-10 20:05:31 +01:00