Merge "SoundPool: Enable multithreaded track start" into main am: 913c46b911

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/2905329

Change-Id: I4fca0711fde4822b8da931a4bfcf5125d041dc70
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>