continueLoading shouldn't return true unless it's done
something. Always returning true if endOfStream was
causing CompositeSequenceableLoader.continueLoading to
loop forever.
It looks like the same issue exists in ChunkSampleStream
as well, although I can't seem to provoke DASH or SS
playbacks into doing anything bad as a result.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=139559834
