[visionOS] Multi-window audio is coming from wrong location

https://bugs.webkit.org/show_bug.cgi?id=274493
rdar://128499204

Reviewed by Andy Estes and Sam Weinig.

Initially, a MediaPlayerPrivateAVFoundationObjC will have an AVPlayer but no AVPlayerLayer, so
will get the "default" spatial tracking label. When an AVPlayerLayer is created (or destroyed!)
the tracking label will need to be re-calculated.

* Source/WebCore/platform/graphics/avfoundation/objc/MediaPlayerPrivateAVFoundationObjC.mm:
(WebCore::MediaPlayerPrivateAVFoundationObjC::createAVPlayerLayer):
(WebCore::MediaPlayerPrivateAVFoundationObjC::updateSpatialTrackingLabel):

Canonical link: https://commits.webkit.org/279103@main

Source/WebCore/platform/graphics/avfoundation/objc/MediaPlayerPrivateAVFoundationObjC.mm

@@ -669,6 +669,9 @@ static WallTime toSystemClockTime(NSDate *date)
         [m_videoLayer setPIPModeEnabled:(player->fullscreenMode() & MediaPlayer::VideoFullscreenModePictureInPicture)];
 #endif
 
+#if HAVE(SPATIAL_TRACKING_LABEL)
+    updateSpatialTrackingLabel();
+#endif
     setNeedsRenderingModeChanged();
 }
 
@@ -688,6 +691,9 @@ static WallTime toSystemClockTime(NSDate *date)
     m_videoLayer = nil;
     m_haveBeenAskedToCreateLayer = false;
 
+#if HAVE(SPATIAL_TRACKING_LABEL)
+    updateSpatialTrackingLabel();
+#endif
     setNeedsRenderingModeChanged();
 }
 
@@ -4085,24 +4091,28 @@ void determineChangedTracksFromNewTracksAndOldItems(MediaSelectionGroupAVFObjC*
         return;
 
     if (!m_spatialTrackingLabel.isNull()) {
+        INFO_LOG(LOGIDENTIFIER, "Explicitly set STSLabel: ", m_spatialTrackingLabel);
         [m_avPlayer _setSTSLabel:m_spatialTrackingLabel];
         return;
     }
 
     if (m_videoLayer) {
         // Let AVPlayer manage setting the spatial tracking label in its AVPlayerLayer itself;
+        INFO_LOG(LOGIDENTIFIER, "No videoLayer, set STSLabel: nil");
         [m_avPlayer _setSTSLabel:nil];
         return;
     }
 
     if (!m_defaultSpatialTrackingLabel.isNull()) {
         // If a default spatial tracking label was explicitly set, use it.
+        INFO_LOG(LOGIDENTIFIER, "Default STSLabel: ", m_defaultSpatialTrackingLabel);
         [m_avPlayer _setSTSLabel:m_defaultSpatialTrackingLabel];
         return;
     }
 
     // If there is no AVPlayerLayer, and no default spatial tracking label is available, use the session's spatial tracking label.
     AVAudioSession *session = [PAL::getAVAudioSessionClass() sharedInstance];
+    INFO_LOG(LOGIDENTIFIER, "AVAudioSession label: ", session.spatialTrackingLabel);
     [m_avPlayer _setSTSLabel:session.spatialTrackingLabel];
 }
 #endif