Some events may arrive after the playlist is cleared (e.g. load
cancellation). In this case, the DefaultPlaybackSessionManager may
create a new session for the already removed item.
We already have checks in place that ignore events with old
windowSequenceNumbers, but these checks only work if the current
session is set (i.e. the playlist is non-empty). The fix is to add
the same check for empty playlists by keeping note of the last
removed window sequence number.
PiperOrigin-RevId: 541870812
(cherry picked from commit e0191ddded1754cc31b025493970240aeb08a46e)
3561258949