APN can't be updated because onkey() method is not invoked when user presses the virtual back key. The ApnEditor was changed from Activity to Fragment in Android N. A fragment can't receive onKey() event without calling setFocusableInTouchMode(true). Test: manual - updated apn setting, then pressed back Bug: 32815214 Change-Id: I7824e84bd617d2057a61f4198fa7fd50f123bc8e