_exempt_from_layout?

# File actionpack/lib/action_view/base.rb, line 341
      def _exempt_from_layout?(template_path) #:nodoc:
        template = _pick_template(template_path).to_s
        @@exempt_from_layout.any? { |ext| template =~ ext }
      rescue ActionView::MissingTemplate
        return false
      end