Merge "AudioFlinger: Refactor SyncEvent" am: b87f4cadbf am: eb60033ad1 am: 8385fb5f34

Original change: https://android-review.googlesource.com/c/platform/frameworks/av/+/2599067

Change-Id: Ic653c7ea5e82e44e94ce2a3d38d81607a6df6238
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>