Not user generated accessibility events can change the interrogation allowing window.

1. Events not generated by the user can change the interrogation allowing window
   unpredicatably. For example when a ListView lays out its children it fires an
   accessibility events and changes the currently active window while the user
   interaction may be happening in another window say a dialog. Now the interrogation
   allowing window is changed when a new window is shown or the user has touch
   explored it.

bug:5074116

Change-Id: I8dde12bbec807d32445a781eedced9b95312b3e2