In the context of Picture-in-Picture, we currently use the first Media Session to be created (independently of the frame). This means we could show a Skip Ad button for a PiP video from another frame. Ideally, we should have a Media Session per frame, not per tab.

Background: https://chromium-review.googlesource.com/c/chromium/src/+/1393331/34/content/browser/picture_in_picture/picture_in_picture_window_controller_impl.cc#74