Method attachShadowDoc

src/multidoc-manager.js:219–251

* Implementation for `attachShadowDoc` function. Attaches the shadow doc and * configures ampdoc for it. * @param {!Element} hostElement * @param {!Document} doc * @param {string} url * @param {!{[key: string]: string}=} opt_initParams * @return {!./runtime.ShadowDoc}

(hostElement, doc, url, opt_initParams)

   * @return {!./runtime.ShadowDoc}
   */
  attachShadowDoc(hostElement, doc, url, opt_initParams) {
    user().assertString(url);
    dev().fine(TAG, 'Attach shadow doc:', doc);
    // TODO(dvoytenko, #9490): once stable, port full document case to emulated
    // stream.
    return this.attachShadowDoc_(
      hostElement,
      url,
      opt_initParams,
      (amp, shadowRoot, ampdoc) => {
        // Install extensions.
        this.mergeShadowHead_(ampdoc, shadowRoot, doc);

        // Append body.
        if (doc.body) {
          const body = importShadowBody(shadowRoot, doc.body, /* deep */ true);
          body.classList.add('amp-shadow');
          ampdoc.setBody(body);
        }

        // TODO(dvoytenko): find a better and more stable way to make content
        // visible. E.g. integrate with dynamic classes. In shadow case
        // specifically, we have to wait for stubbing to complete, which may
        // take awhile due to importNode.
        setTimeout(() => {
          ampdoc.signals().signal(CommonSignals_Enum.RENDER_START);
          setStyle(hostElement, 'visibility', 'visible');
        }, 50);

        return Promise.resolve();
      }
    );
  }

  /**
   * Implementation for `attachShadowDocAsStream` function. Attaches the shadow