Merge "Optimize attaching / detaching audio mixes." into udc-dev am: 12504654 am: c51d4e7d

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/22607657



Change-Id: If8a803b7a2e6d3f33bb1b0538162e00a6e89fa6d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>