SDK / exoplayer

This is implemented in the same way as in MediaCodecRenderer.

Move codec != null guard into feedInputBuffer to handle the case of an input
format change with no dequeued buffers where the codec can't be reinitialized
immediately.

Issue: #2111

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=140864942