Merge "Use MediaPlayer in a background thread." into tm-dev am: a7358c9d am: 9fea320f

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/18723155



Change-Id: I8def3146069760a42da467d5bdbb386c6ba2096a
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>