Also use MediaCodec buffer flag constants instead of those on MediaExtractor.
This is in preparation for merging InputBuffer and SampleHolder.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=117810136
- The old approach was technically incorrect, because the checks
were "capacity < sampleSize" and hence neglected the fact that
the buffer position may be greater than 0 (e.g. if the caller
wants to prefix the sample with some additional data).
- Also proactively throw an exception if the buffer is too small,
rather than wait for the failure when we actually do the write.
