This code should live in the `CameraController` if it is controlling the camera. Put the low-level listener code in `App` and emit a new event that can be listened for in `CameraController`.

```js
// In app.js
navigator.mozSettings.addObserver( 'private.broadcast.attention_screen_opening', function(event) {
  if (event.settingValue) {
    self.emit('attentionscreenopened');
  }
});
```

```js
// In controllers/camera.js
this.app.on('attentionscreenopened', this.camera.stopRecording);
```