I added this call to `handleNewKeyboards()` based on your suggestion in [this outdated diff](https://github.com/mozilla-b2g/gaia/pull/9073#discussion_r3963771), where you were pointing out that there might be a race condition: the keyboard app could enable a new keyboard before that keyboard is added to the `enabledKeyboardNames[]` array, which is what `handleNewKeyboards()` takes care of.

The Settings app makes sure to set both `keyboard.current` and `keyboard.layouts._`, thus avoiding an unnecessary read of `keyboard_layouts.json` for the Keyboard app (which would have been required if only `keyboard.current` was set to activate the associated layout).