chromium/chrome/browser/resources/chromeos/add_supervision/add_supervision_app.html

<cr-view-manager id="viewManager">
    <add-supervision-ui id="add-supervision-ui" slot="view">
    </add-supervision-ui>
    <supervised-user-error id="supervised-user-error" slot="view">
    </supervised-user-error>
    <supervised-user-offline id="supervised-user-offline" slot="view">
    </supervised-user-offline>
</cr-view-manager>