AVKit macOS xcode13.0 beta3

#AVKit.framework https://github.com/xamarin/xamarin-macios/pull/12551

diff -ruN /Applications/Xcode_13.0.0-beta2.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/System/Library/Frameworks/AVKit.framework/Headers/AVPictureInPictureController_AVSampleBufferDisplayLayerSupport.h /Applications/Xcode_13.0.0-beta3.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/System/Library/Frameworks/AVKit.framework/Headers/AVPictureInPictureController_AVSampleBufferDisplayLayerSupport.h
--- /Applications/Xcode_13.0.0-beta2.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/System/Library/Frameworks/AVKit.framework/Headers/AVPictureInPictureController_AVSampleBufferDisplayLayerSupport.h	2021-06-22 17:33:00.000000000 -0400
+++ /Applications/Xcode_13.0.0-beta3.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/System/Library/Frameworks/AVKit.framework/Headers/AVPictureInPictureController_AVSampleBufferDisplayLayerSupport.h	2021-07-10 09:45:54.000000000 -0400
@@ -87,6 +87,21 @@
 */
 - (void)pictureInPictureController:(AVPictureInPictureController *)pictureInPictureController skipByInterval:(CMTime)skipInterval completionHandler:(void (^)(void))completionHandler NS_SWIFT_NAME(pictureInPictureController(_:skipByInterval:completion:));
 
+
+@optional
+
+/*!
+	@method		pictureInPictureControllerShouldProhibitBackgroundAudioPlayback:
+	@param		pictureInPictureController
+				The Picture in Picture controller.
+	@abstract	Allows the delegate to indicate whether background audio playback should always be prohibited.
+	@discussion	If implemented, this optional method will be called once for each invocation of invalidatePlaybackState to allow the delegate to indicate whether or not audio playback should be prohibited when the picture in picture window is in the background.
+ 
+				Note that background in this context has a seperate meaning from application background used in UIKit. Here, background defines the state of the picture in picture window itself rather than the application.
+	@returns	A boolean value indicating whether or not background audio playback is always prohibited.
+*/
+- (BOOL)pictureInPictureControllerShouldProhibitBackgroundAudioPlayback:(AVPictureInPictureController *)pictureInPictureController NS_SWIFT_NAME(pictureInPictureControllerShouldProhibitBackgroundAudioPlayback(_:));
+
 @end