Add up-to-date ExoPlayer copy

Generated using:
./download_exoplayer.py --commit 8e57d3715f9092d5ec54ebe2e538f34bfcc34479

Bug: 223572414
Test: N/A. This just drops code into the tree.
Change-Id: Id5615e24b3a77d2978df70591b96168e7ee21ce3
4802 files changed