update to exoplayer minsdk19 am: 0fbe9bb3aa am: 21b20f52c6

Original change: https://android-review.googlesource.com/c/platform/external/exoplayer/+/2852985

Change-Id: I8d1543c24fcc297871524f58277cfe2c9dce188a
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>