AudioTrack: reduce retrograde motion spew

Change-Id: I96aced52b136ceea924aa3d9ef56374dd4c49784
Signed-off-by: Phil Burk <philburk@google.com>
diff --git a/include/media/AudioTrack.h b/include/media/AudioTrack.h
index 51d40bb..0ccd19e 100644
--- a/include/media/AudioTrack.h
+++ b/include/media/AudioTrack.h
@@ -839,6 +839,7 @@
                                                     // only used for offloaded and direct tracks.
 
     bool                    mPreviousTimestampValid;// true if mPreviousTimestamp is valid
+    bool                    mRetrogradeMotionReported; // reduce log spam
     AudioTimestamp          mPreviousTimestamp;     // used to detect retrograde motion
 
     audio_output_flags_t    mFlags;