hasOverlayPermission
Checks if the application has permission to draw overlays on top of other apps.
On devices running Android Marshmallow (API level 23) or higher, this method verifies whether the app has been granted the SYSTEM_ALERT_WINDOW permission. On lower versions, it returns true by default as this permission is not required.
Return
true if the overlay permission is granted, or if the platform version is lower than API level 23.