Update region if it has changed after rendering footer (bug 1066774)

Follow-up to #663 
https://bugzilla.mozilla.org/show_bug.cgi?id=1066774

We do wait for the consumer info promise before triggering 'navigate', so the region in the views is OK, but the footer can be rendered before that.


That method has the worst signature of all our code. the first parameter is the default region to use if no region was returned.