Use current position code when checking if AudioTrack has pending data

We currently rely on the raw playback head position to check if any
data is pending in the AudioTrack (e.g. to know if the renderer is
still ready). We can use the value returned from getCurrentPositionUs
instead to align the "isReady" logic with the playback position logic.

This has the side effect that getPlaybackHeadPosition position is called
less often when the position is obtained via getTimestamp.

PiperOrigin-RevId: 514747613

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

@@ -420,7 +420,8 @@ public void handleEndOfStream(long writtenFrames) {
    * @return Whether the audio track has any pending data to play out.
    */
   public boolean hasPendingData(long writtenFrames) {
-    return writtenFrames > getPlaybackHeadPosition() || forceHasPendingData();
+    return writtenFrames > durationUsToFrames(getCurrentPositionUs(/* sourceEnded= */ false))
+        || forceHasPendingData();
   }
 
   /**
@@ -542,6 +543,10 @@ private long framesToDurationUs(long frameCount) {
     return (frameCount * C.MICROS_PER_SECOND) / outputSampleRate;
   }
 
+  private long durationUsToFrames(long durationUs) {
+    return (durationUs * outputSampleRate) / C.MICROS_PER_SECOND;
+  }
+
   private void resetSyncParams() {
     smoothedPlayheadOffsetUs = 0;
     playheadOffsetCount = 0;
@@ -591,7 +596,7 @@ private long getPlaybackHeadPosition() {
       long elapsedTimeSinceStopUs = (currentTimeMs * 1000) - stopTimestampUs;
       long mediaTimeSinceStopUs =
           Util.getMediaDurationForPlayoutDuration(elapsedTimeSinceStopUs, audioTrackPlaybackSpeed);
-      long framesSinceStop = (mediaTimeSinceStopUs * outputSampleRate) / C.MICROS_PER_SECOND;
+      long framesSinceStop = durationUsToFrames(mediaTimeSinceStopUs);
       return min(endPlaybackHeadPosition, stopPlaybackHeadPosition + framesSinceStop);
     }
     if (currentTimeMs - lastRawPlaybackHeadPositionSampleTimeMs