SDK / exoplayer

FrameworkSampleSource will still be useful for audio, where
sample interleaving isn't an issue. We could optionally add
a "don't wait for first frame" boolean to the video renderer
if we *really* need to keep some form of this workaround in
place, but I'd rather not do so for now.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=119733224