how can i received callback when pip was closed

when pip window was closed, my app still playing the video. i'm unwilling to stop video when onStop called, because maybe it just restored fullscreen. So i hope receive closed callback, i can really destroy activity and release my MediaPlayer.

No file or test is identified in the issue. Start by locating the sample's picture-in-picture lifecycle handling and determine how it distinguishes a real PiP close from fullscreen restoration. Done means the app can release its MediaPlayer only after a confirmed PiP close, without stopping playback during restoration.

Written by the indexing model from the issue text.