Update UI in paused state to support multi-window mode
In Android N's multi-window mode, the app that doesn't have focus is in the paused state. We should move all our calls to register/unregister event handlers, refresh content, etc, from onPause/onResume to onStart/onStop so that the UI is updated in the paused state.
https://developer.android.com/guide/topics/ui/multi-window.html