chromium/mojo/public/tools/bindings/generators/cpp_templates/feature_definition.tmpl

BASE_FEATURE({{feature.name}},
             {{feature|feature_name}},
{%- if feature|is_feature_on_by_default %}
             base::FEATURE_ENABLED_BY_DEFAULT
{%- else %}
             base::FEATURE_DISABLED_BY_DEFAULT
{%- endif %}
             );