SDK / exoplayer

*** Reason for rollback ***

Doesn't work because trackOutputProvider can be null when extracting init data.

*** Original change description ***

Don't copy primary-track format to non-primary tracks

Copying non-primary-track formats to non-primary tracks
looks non-trivial (I tried; went down a dead-end), so
leaving that for now.

***

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=166883654