[visionOS] Safari YouTube audio location stays stationary when window…

… is moved while viewing other tab (audio is not spatial)

https://bugs.webkit.org/show_bug.cgi?id=260364
<radar://112181086>

Reviewed by Andy Estes.

Set the STSLabel when the viewer becomes invisible so audio follows the scene.

Set it back to nil when the viewer becomes visible to restore the current behavior.

* Source/WebCore/platform/graphics/avfoundation/objc/MediaPlayerPrivateMediaSourceAVFObjC.mm:
(WebCore::MediaPlayerPrivateMediaSourceAVFObjC::setPageIsVisible):

* Source/WebCore/PAL/pal/spi/cocoa/AVFoundationSPI.h:
Stage SPI for non-internal clients.

Canonical link: https://commits.webkit.org/267018@main

Source/WebCore/PAL/pal/spi/cocoa/AVFoundationSPI.h

@@ -497,3 +497,10 @@ NS_ASSUME_NONNULL_BEGIN
 NS_ASSUME_NONNULL_END
 #endif
 
+#if __has_include(<AVFoundation/AVSampleBufferVideoRenderer_Private.h>)
+#import <AVFoundation/AVSampleBufferVideoRenderer_Private.h>
+#elif PLATFORM(VISION)
+@interface AVSampleBufferVideoRenderer (AVSampleBufferVideoRendererWebKitPrivate)
+@property (nonatomic, copy, nullable, getter=_STSLabel) NSString *STSLabel SPI_AVAILABLE(ios(15.0)) API_UNAVAILABLE(macos, tvos, watchos);
+@end
+#endif

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

@@ -439,6 +439,14 @@ void getSupportedTypes(HashSet<String, ASCIICaseInsensitiveHash>& types) const f
     m_visible = visible;
     if (m_visible)
         acceleratedRenderingStateChanged();
+
+#if PLATFORM(VISION)
+    if (!visible) {
+        AVAudioSession *session = [PAL::getAVAudioSessionClass() sharedInstance];
+        [m_sampleBufferDisplayLayer sampleBufferRenderer].STSLabel = session.spatialTrackingLabel;
+    } else
+        [m_sampleBufferDisplayLayer sampleBufferRenderer].STSLabel = nil;
+#endif
 }
 
 MediaTime MediaPlayerPrivateMediaSourceAVFObjC::durationMediaTime() const