REGRESSION(260575@main): TestWebKitAPI.AudioRoutingArbitration.Deleti…

…on times out with UI-side-compositing enabled

https://bugs.webkit.org/show_bug.cgi?id=253670
rdar://106322713

Reviewed by Ryosuke Niwa.

When we did the "don't host layers from the WebContent process" work, we re-used the
PlaybackSessionManager/VideoFullscreenManager codepath from element fullscreen and
picture-in-picture to handle creation and sizing of the video layer in the UI process. This caused
a pre-existing bug where a fullscreened HTMLMediaElement would never be destroyed (due to having
eventListeners) to now apply to all HTMLMediaElements displayed in a page.

The eventListeners aren't removed because a boolean ivar intended to track whether eventListeners
were added was never set to true. Once that ivar is correctly set, the test passes.

* Source/WebCore/platform/cocoa/PlaybackSessionModelMediaElement.mm:
(WebCore::PlaybackSessionModelMediaElement::setMediaElement):

Canonical link: https://commits.webkit.org/261503@main

Source/WebCore/platform/cocoa/PlaybackSessionModelMediaElement.mm

@@ -103,6 +103,7 @@
         textTracks.addEventListener(events.addtrackEvent, *this, false);
         textTracks.addEventListener(events.changeEvent, *this, false);
         textTracks.addEventListener(events.removetrackEvent, *this, false);
+        m_isListening = true;
     }
 
     updateForEventName(eventNameAll());