Merge "Early return when mA2dp is null (disconnected) to avoid null object reference" am: d479859c8e am: 43c7ce7a6d

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/2633292

Change-Id: Ib02a15655974aa8cb3da637967327de3aea41eb6
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>