Make the Cast demo app absorb remote queue changes

Necessary in two scenarios:
+ When the demo app starts casting to a receiver app that already
  had a queue.
+ When two demo apps are connected to the same receiver app and
  both make modifications.

PiperOrigin-RevId: 230546851

demos/cast/src/main/java/com/google/android/exoplayer2/castdemo/DefaultReceiverPlayerManager.java

@@ -63,7 +63,7 @@ import java.util.ArrayList;
   private final SimpleExoPlayer exoPlayer;
   private final CastPlayer castPlayer;
   private final ArrayList<MediaItem> mediaQueue;
-  private final QueuePositionListener queuePositionListener;
+  private final QueueChangesListener queueChangesListener;
   private final ConcatenatingMediaSource concatenatingMediaSource;
 
   private boolean castMediaQueueCreationPending;
@@ -71,32 +71,21 @@ import java.util.ArrayList;
   private Player currentPlayer;
 
   /**
-   * @param queuePositionListener A {@link QueuePositionListener} for queue position changes.
+   * Creates a new manager for {@link SimpleExoPlayer} and {@link CastPlayer}.
+   *
+   * @param queueChangesListener A {@link QueueChangesListener} for queue position changes.
    * @param localPlayerView The {@link PlayerView} for local playback.
    * @param castControlView The {@link PlayerControlView} to control remote playback.
    * @param context A {@link Context}.
    * @param castContext The {@link CastContext}.
    */
-  public static DefaultReceiverPlayerManager createPlayerManager(
-      QueuePositionListener queuePositionListener,
-      PlayerView localPlayerView,
-      PlayerControlView castControlView,
-      Context context,
-      CastContext castContext) {
-    DefaultReceiverPlayerManager defaultReceiverPlayerManager =
-        new DefaultReceiverPlayerManager(
-            queuePositionListener, localPlayerView, castControlView, context, castContext);
-    defaultReceiverPlayerManager.init();
-    return defaultReceiverPlayerManager;
-  }
-
-  private DefaultReceiverPlayerManager(
-      QueuePositionListener queuePositionListener,
+  public DefaultReceiverPlayerManager(
+      QueueChangesListener queueChangesListener,
       PlayerView localPlayerView,
       PlayerControlView castControlView,
       Context context,
       CastContext castContext) {
-    this.queuePositionListener = queuePositionListener;
+    this.queueChangesListener = queueChangesListener;
     this.localPlayerView = localPlayerView;
     this.castControlView = castControlView;
     mediaQueue = new ArrayList<>();
@@ -113,6 +102,8 @@ import java.util.ArrayList;
     castPlayer.addListener(this);
     castPlayer.setSessionAvailabilityListener(this);
     castControlView.setPlayer(castPlayer);
+
+    setCurrentPlayer(castPlayer.isCastSessionAvailable() ? castPlayer : exoPlayer);
   }
 
   // Queue manipulation methods.
@@ -287,10 +278,6 @@ import java.util.ArrayList;
 
   // Internal methods.
 
-  private void init() {
-    setCurrentPlayer(castPlayer.isCastSessionAvailable() ? castPlayer : exoPlayer);
-  }
-
   private void updateCurrentItemIndex() {
     int playbackState = currentPlayer.getPlaybackState();
     maybeSetCurrentItemAndNotify(
@@ -372,7 +359,7 @@ import java.util.ArrayList;
     if (this.currentItemIndex != currentItemIndex) {
       int oldIndex = this.currentItemIndex;
       this.currentItemIndex = currentItemIndex;
-      queuePositionListener.onQueuePositionChanged(oldIndex, currentItemIndex);
+      queueChangesListener.onQueuePositionChanged(oldIndex, currentItemIndex);
     }
   }
 

demos/cast/src/main/java/com/google/android/exoplayer2/castdemo/MainActivity.java

@@ -49,7 +49,7 @@ import java.util.Collections;
  * Cast extension.
  */
 public class MainActivity extends AppCompatActivity
-    implements OnClickListener, PlayerManager.QueuePositionListener {
+    implements OnClickListener, PlayerManager.QueueChangesListener {
 
   private final MediaItem.Builder mediaItemBuilder;
 
@@ -121,8 +121,8 @@ public class MainActivity extends AppCompatActivity
     switch (applicationId) {
       case CastMediaControlIntent.DEFAULT_MEDIA_RECEIVER_APPLICATION_ID:
         playerManager =
-            DefaultReceiverPlayerManager.createPlayerManager(
-                /* queuePositionListener= */ this,
+            new DefaultReceiverPlayerManager(
+                /* queueChangesListener= */ this,
                 localPlayerView,
                 castControlView,
                 /* context= */ this,
@@ -162,7 +162,7 @@ public class MainActivity extends AppCompatActivity
         .show();
   }
 
-  // PlayerManager.QueuePositionListener implementation.
+  // PlayerManager.QueueChangesListener implementation.
 
   @Override
   public void onQueuePositionChanged(int previousIndex, int newIndex) {
@@ -174,6 +174,11 @@ public class MainActivity extends AppCompatActivity
     }
   }
 
+  @Override
+  public void onQueueContentsExternallyChanged() {
+    mediaQueueListAdapter.notifyDataSetChanged();
+  }
+
   // Internal methods.
 
   private View buildSampleListView() {

demos/cast/src/main/java/com/google/android/exoplayer2/castdemo/PlayerManager.java

@@ -22,14 +22,14 @@ import com.google.android.exoplayer2.ext.cast.MediaItem;
 /** Manages the players in the Cast demo app. */
 interface PlayerManager {
 
-  /** Listener for changes in the media queue playback position. */
-  interface QueuePositionListener {
+  /** Listener for changes in the media queue. */
+  interface QueueChangesListener {
 
-    /**
-     * Called when the currently played item of the media queue changes.
-     */
+    /** Called when the currently played item of the media queue changes. */
     void onQueuePositionChanged(int previousIndex, int newIndex);
 
+    /** Called when the media queue changes due to modifications not caused by this manager. */
+    void onQueueContentsExternallyChanged();
   }
 
   /** Redirects the given {@code keyEvent} to the active player. */