Returns a list of content types from the models defined in settings.

def _get_seo_content_types(seo_models):
    """Returns a list of content types from the models defined in settings."""
    try:
        return [ContentType.objects.get_for_model(m).id for m in seo_models]
    except Exception:  # previously caught DatabaseError
        # Return an empty list if this is called too early
        return []