set mediaSession flags properly and keep queue in sync when timeline changes

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=164774783

extensions/mediasession/src/main/java/com/google/android/exoplayer2/ext/mediasession/MediaSessionConnector.java

@@ -73,6 +73,10 @@ public final class MediaSessionConnector {
   }
   }
 
 
   public static final String EXTRAS_PITCH = "EXO_PITCH";
   public static final String EXTRAS_PITCH = "EXO_PITCH";
+  private static final int BASE_MEDIA_SESSION_FLAGS = MediaSessionCompat.FLAG_HANDLES_MEDIA_BUTTONS
+      | MediaSessionCompat.FLAG_HANDLES_TRANSPORT_CONTROLS;
+  private static final int EDITOR_MEDIA_SESSION_FLAGS = BASE_MEDIA_SESSION_FLAGS
+      | MediaSessionCompat.FLAG_HANDLES_QUEUE_COMMANDS;
 
 
   /**
   /**
    * Interface to which playback preparation actions are delegated.
    * Interface to which playback preparation actions are delegated.
@@ -318,7 +322,6 @@ public final class MediaSessionConnector {
 
 
   private Player player;
   private Player player;
   private CustomActionProvider[] customActionProviders;
   private CustomActionProvider[] customActionProviders;
-  private int currentWindowIndex;
   private Map<String, CustomActionProvider> customActionMap;
   private Map<String, CustomActionProvider> customActionMap;
   private ErrorMessageProvider errorMessageProvider;
   private ErrorMessageProvider errorMessageProvider;
   private PlaybackPreparer playbackPreparer;
   private PlaybackPreparer playbackPreparer;
@@ -369,8 +372,7 @@ public final class MediaSessionConnector {
     this.handler = new Handler(Looper.myLooper() != null ? Looper.myLooper()
     this.handler = new Handler(Looper.myLooper() != null ? Looper.myLooper()
         : Looper.getMainLooper());
         : Looper.getMainLooper());
     this.doMaintainMetadata = doMaintainMetadata;
     this.doMaintainMetadata = doMaintainMetadata;
-    mediaSession.setFlags(MediaSessionCompat.FLAG_HANDLES_MEDIA_BUTTONS
-        | MediaSessionCompat.FLAG_HANDLES_TRANSPORT_CONTROLS);
+    mediaSession.setFlags(BASE_MEDIA_SESSION_FLAGS);
     mediaController = mediaSession.getController();
     mediaController = mediaSession.getController();
     mediaSessionCallback = new MediaSessionCallback();
     mediaSessionCallback = new MediaSessionCallback();
     exoPlayerEventListener = new ExoPlayerEventListener();
     exoPlayerEventListener = new ExoPlayerEventListener();
@@ -433,6 +435,8 @@ public final class MediaSessionConnector {
    */
    */
   public void setQueueEditor(QueueEditor queueEditor) {
   public void setQueueEditor(QueueEditor queueEditor) {
     this.queueEditor = queueEditor;
     this.queueEditor = queueEditor;
+    mediaSession.setFlags(queueEditor == null ? BASE_MEDIA_SESSION_FLAGS
+        : EDITOR_MEDIA_SESSION_FLAGS);
   }
   }
 
 
   private void updateMediaSessionPlaybackState() {
   private void updateMediaSessionPlaybackState() {
@@ -583,11 +587,20 @@ public final class MediaSessionConnector {
 
 
   private class ExoPlayerEventListener implements Player.EventListener {
   private class ExoPlayerEventListener implements Player.EventListener {
 
 
+    private int currentWindowIndex;
+    private int currentWindowCount;
+
     @Override
     @Override
     public void onTimelineChanged(Timeline timeline, Object manifest) {
     public void onTimelineChanged(Timeline timeline, Object manifest) {
       if (queueNavigator != null) {
       if (queueNavigator != null) {
         queueNavigator.onTimelineChanged(player);
         queueNavigator.onTimelineChanged(player);
       }
       }
+      int windowCount = player.getCurrentTimeline().getWindowCount();
+      if (currentWindowCount != windowCount) {
+        // active queue item and queue navigation actions may need to be updated
+        updateMediaSessionPlaybackState();
+      }
+      currentWindowCount = windowCount;
       currentWindowIndex = player.getCurrentWindowIndex();
       currentWindowIndex = player.getCurrentWindowIndex();
       updateMediaSessionMetadata();
       updateMediaSessionMetadata();
     }
     }