Fix AudioTrack presentationComplete regression

Bug: 27310929
Change-Id: Id52299660d90b07220a4fd9996da53fe755a41f1
diff --git a/services/audioflinger/Threads.h b/services/audioflinger/Threads.h
index 507f197..42b3266 100644
--- a/services/audioflinger/Threads.h
+++ b/services/audioflinger/Threads.h
@@ -693,6 +693,7 @@
     volatile int32_t                mSuspended;
 
     int64_t                         mBytesWritten;
+    int64_t                         mFramesWritten; // not reset on standby
 private:
     // mMasterMute is in both PlaybackThread and in AudioFlinger.  When a
     // PlaybackThread needs to find out if master-muted, it checks it's local