Avoid creating empty playback metrics

In some cases we create empty playback metrics with no corresponding
events (e.g. when an app seeks to a new media item and immediately
releases the player). There is no benefit in having completely empty
metrics entries, so it's cleaner to not report them in such cases.

#minor-release

PiperOrigin-RevId: 425609010

library/core/src/main/java/com/google/android/exoplayer2/analytics/MediaMetricsListener.java

@@ -134,6 +134,7 @@ public final class MediaMetricsListener
   private int droppedFrames;
   private int droppedFrames;
   private int playedFrames;
   private int playedFrames;
   private int audioUnderruns;
   private int audioUnderruns;
+  private boolean reportedEventsForCurrentSession;
 
 
   /**
   /**
    * Creates the listener.
    * Creates the listener.
@@ -359,6 +360,7 @@ public final class MediaMetricsListener
             .setSubErrorCode(errorInfo.subErrorCode)
             .setSubErrorCode(errorInfo.subErrorCode)
             .setException(error)
             .setException(error)
             .build());
             .build());
+    reportedEventsForCurrentSession = true;
     pendingPlayerError = null;
     pendingPlayerError = null;
   }
   }
 
 
@@ -429,6 +431,7 @@ public final class MediaMetricsListener
     int newPlaybackState = resolveNewPlaybackState(player);
     int newPlaybackState = resolveNewPlaybackState(player);
     if (currentPlaybackState != newPlaybackState) {
     if (currentPlaybackState != newPlaybackState) {
       currentPlaybackState = newPlaybackState;
       currentPlaybackState = newPlaybackState;
+      reportedEventsForCurrentSession = true;
       playbackSession.reportPlaybackStateEvent(
       playbackSession.reportPlaybackStateEvent(
           new PlaybackStateEvent.Builder()
           new PlaybackStateEvent.Builder()
               .setState(currentPlaybackState)
               .setState(currentPlaybackState)
@@ -561,6 +564,7 @@ public final class MediaMetricsListener
     } else {
     } else {
       builder.setTrackState(TrackChangeEvent.TRACK_STATE_OFF);
       builder.setTrackState(TrackChangeEvent.TRACK_STATE_OFF);
     }
     }
+    reportedEventsForCurrentSession = true;
     playbackSession.reportTrackChangeEvent(builder.build());
     playbackSession.reportTrackChangeEvent(builder.build());
   }
   }
 
 
@@ -586,12 +590,11 @@ public final class MediaMetricsListener
     }
     }
     metricsBuilder.setPlaybackType(
     metricsBuilder.setPlaybackType(
         window.isLive() ? PlaybackMetrics.PLAYBACK_TYPE_LIVE : PlaybackMetrics.PLAYBACK_TYPE_VOD);
         window.isLive() ? PlaybackMetrics.PLAYBACK_TYPE_LIVE : PlaybackMetrics.PLAYBACK_TYPE_VOD);
+    reportedEventsForCurrentSession = true;
   }
   }
 
 
   private void finishCurrentSession() {
   private void finishCurrentSession() {
-    if (metricsBuilder == null) {
-      return;
-    }
+    if (metricsBuilder != null && reportedEventsForCurrentSession) {
       metricsBuilder.setAudioUnderrunCount(audioUnderruns);
       metricsBuilder.setAudioUnderrunCount(audioUnderruns);
       metricsBuilder.setVideoFramesDropped(droppedFrames);
       metricsBuilder.setVideoFramesDropped(droppedFrames);
       metricsBuilder.setVideoFramesPlayed(playedFrames);
       metricsBuilder.setVideoFramesPlayed(playedFrames);
@@ -606,6 +609,7 @@ public final class MediaMetricsListener
               ? PlaybackMetrics.STREAM_SOURCE_NETWORK
               ? PlaybackMetrics.STREAM_SOURCE_NETWORK
               : PlaybackMetrics.STREAM_SOURCE_UNKNOWN);
               : PlaybackMetrics.STREAM_SOURCE_UNKNOWN);
       playbackSession.reportPlaybackMetrics(metricsBuilder.build());
       playbackSession.reportPlaybackMetrics(metricsBuilder.build());
+    }
     metricsBuilder = null;
     metricsBuilder = null;
     activeSessionId = null;
     activeSessionId = null;
     audioUnderruns = 0;
     audioUnderruns = 0;
@@ -614,6 +618,7 @@ public final class MediaMetricsListener
     currentVideoFormat = null;
     currentVideoFormat = null;
     currentAudioFormat = null;
     currentAudioFormat = null;
     currentTextFormat = null;
     currentTextFormat = null;
+    reportedEventsForCurrentSession = false;
   }
   }
 
 
   private static int getTrackChangeReason(@C.SelectionReason int trackSelectionReason) {
   private static int getTrackChangeReason(@C.SelectionReason int trackSelectionReason) {