Fix issue caused by using ForwardingPlayer and StyledPlayerControlView

StyledPlayerControlView was checking whether the player is an ExoPlayer
instance to set the track selector. This means that, if apps were
wrapping an ExoPlayer in a ForwardingPlayer (to replace a
ControlDispatcher for example), the track selector wasn't set anymore.

PiperOrigin-RevId: 391776305

RELEASENOTES.md

@@ -1,5 +1,11 @@
 # Release notes
 
+### dev-v2 (not yet released)
+
+*   Core Library:
+    *   Fix track selection in `StyledPlayerControlView` when using
+        `ForwardingPlayer`.
+
 ### 2.15.0 (2021-08-10)
 
 *   Core Library:

library/common/src/main/java/com/google/android/exoplayer2/ForwardingPlayer.java

@@ -615,6 +615,11 @@ public void setDeviceMuted(boolean muted) {
     player.setDeviceMuted(muted);
   }
 
+  /** Returns the {@link Player} to which operations are forwarded. */
+  public Player getWrappedPlayer() {
+    return player;
+  }
+
   @SuppressWarnings("deprecation") // Use of deprecated type for backwards compatibility.
   private static class ForwardingEventListener implements EventListener {
 

library/ui/src/main/java/com/google/android/exoplayer2/ui/StyledPlayerControlView.java

@@ -757,6 +757,9 @@ public void setPlayer(@Nullable Player player) {
     if (player != null) {
       player.addListener(componentListener);
     }
+    if (player instanceof ForwardingPlayer) {
+      player = ((ForwardingPlayer) player).getWrappedPlayer();
+    }
     if (player instanceof ExoPlayer) {
       TrackSelector trackSelector = ((ExoPlayer) player).getTrackSelector();
       if (trackSelector instanceof DefaultTrackSelector) {