[automerger skipped] audio: return accurate frame count when track is flushed am: 8735d0dd6c am: f0a3600370 am: 58721a107f -s ours

am skip reason: skip tag Change-Id I3b04999a29d85a91b54734514cfa93bc93f55c33 with SHA-1 1ed46a2c76 is already in history

Original change: https://android-review.googlesource.com/c/platform/frameworks/av/+/1644226

Change-Id: Ic5f1160bfacb6b3641367765ae8867abbe188383