As AppFW is now part of core AGL since BB/2.0 (and confirmed with CC/3.0), the corresponding layer should be moved from meta-agl-extra to meta-agl.
At the same time, the feature 'agl-appfw-smack' should be enabled by default, by using features dependencies mechanism.
It should be noted that currently, building agl-demo-platform on CC or master without agl-appfw-smack fails: so there's already a strong dependency between AGL and its appfw layer..
This task requires SC approval. - Approved.