I've downloaded the permission checker app and found the foll.
For the permissions on SYSTEM_ALERT_WINDOW and GET_TASKS the foll applications have been displayed-
[Antivirus Free](https://play.google.com/store/apps/details?id=com.zrgiu.antivirus&hl=en),
[Battery Doctor](https://play.google.com/store/apps/details?id=com.ijinshan.kbatterydoctor_en&hl=en),
[Holo Locker](https://play.google.com/store/apps/details?id=com.mobint.locker&hl=en),
[Applock](https://play.google.com/store/apps/details?id=com.domobile.applock&hl=en),