Ensure getPlaybackHeadPosition isn't called if not needed

Once the value returned from AudioTimestampPoller advances, we
only need getPlaybackHeadPosition to sample sync params and
verify the returned timestamp. Both of these happen less often
and we can avoid calling getPlaybackHeadPosition if we don't
actually need it.

PiperOrigin-RevId: 512882170

library/core/src/main/java/com/google/android/exoplayer2/audio/AudioTrackPositionTracker.java

@@ -451,13 +451,13 @@ import java.lang.reflect.Method;
   }
   }
 
 
   private void maybeSampleSyncParams() {
   private void maybeSampleSyncParams() {
+    long systemTimeUs = System.nanoTime() / 1000;
+    if (systemTimeUs - lastPlayheadSampleTimeUs >= MIN_PLAYHEAD_OFFSET_SAMPLE_INTERVAL_US) {
       long playbackPositionUs = getPlaybackHeadPositionUs();
       long playbackPositionUs = getPlaybackHeadPositionUs();
       if (playbackPositionUs == 0) {
       if (playbackPositionUs == 0) {
         // The AudioTrack hasn't output anything yet.
         // The AudioTrack hasn't output anything yet.
         return;
         return;
       }
       }
-    long systemTimeUs = System.nanoTime() / 1000;
-    if (systemTimeUs - lastPlayheadSampleTimeUs >= MIN_PLAYHEAD_OFFSET_SAMPLE_INTERVAL_US) {
       // Take a new sample and update the smoothed offset between the system clock and the playhead.
       // Take a new sample and update the smoothed offset between the system clock and the playhead.
       playheadOffsets[nextPlayheadOffsetIndex] =
       playheadOffsets[nextPlayheadOffsetIndex] =
           Util.getPlayoutDurationForMediaDuration(playbackPositionUs, audioTrackPlaybackSpeed)
           Util.getPlayoutDurationForMediaDuration(playbackPositionUs, audioTrackPlaybackSpeed)
@@ -479,11 +479,11 @@ import java.lang.reflect.Method;
       return;
       return;
     }
     }
 
 
-    maybePollAndCheckTimestamp(systemTimeUs, playbackPositionUs);
+    maybePollAndCheckTimestamp(systemTimeUs);
     maybeUpdateLatency(systemTimeUs);
     maybeUpdateLatency(systemTimeUs);
   }
   }
 
 
-  private void maybePollAndCheckTimestamp(long systemTimeUs, long playbackPositionUs) {
+  private void maybePollAndCheckTimestamp(long systemTimeUs) {
     AudioTimestampPoller audioTimestampPoller = checkNotNull(this.audioTimestampPoller);
     AudioTimestampPoller audioTimestampPoller = checkNotNull(this.audioTimestampPoller);
     if (!audioTimestampPoller.maybePollTimestamp(systemTimeUs)) {
     if (!audioTimestampPoller.maybePollTimestamp(systemTimeUs)) {
       return;
       return;
@@ -492,6 +492,7 @@ import java.lang.reflect.Method;
     // Check the timestamp and accept/reject it.
     // Check the timestamp and accept/reject it.
     long audioTimestampSystemTimeUs = audioTimestampPoller.getTimestampSystemTimeUs();
     long audioTimestampSystemTimeUs = audioTimestampPoller.getTimestampSystemTimeUs();
     long audioTimestampPositionFrames = audioTimestampPoller.getTimestampPositionFrames();
     long audioTimestampPositionFrames = audioTimestampPoller.getTimestampPositionFrames();
+    long playbackPositionUs = getPlaybackHeadPositionUs();
     if (Math.abs(audioTimestampSystemTimeUs - systemTimeUs) > MAX_AUDIO_TIMESTAMP_OFFSET_US) {
     if (Math.abs(audioTimestampSystemTimeUs - systemTimeUs) > MAX_AUDIO_TIMESTAMP_OFFSET_US) {
       listener.onSystemTimeUsMismatch(
       listener.onSystemTimeUsMismatch(
           audioTimestampPositionFrames,
           audioTimestampPositionFrames,