src/service/extensions-impl.js
/**
   * Returns the promise that will be resolved when the extension has been
   * loaded. If necessary, adds the extension script to the page.
   * @param {string} extensionId
   * @return {!Promise<!ExtensionDef>}
   */
Returns the promise that will be resolved when the extension has been
loaded. If necessary, adds the extension script to the page.
@param {string} extensionId
@return {!Promise}
Returns the promise that will be resolved when the extension has been loaded . If necessary adds the extension script to the page . @param { string } extensionId @return { !Promise }
preloadExtension(extensionId) {
    if (extensionId == 'amp-embed') {
      extensionId = 'amp-ad';
    }
    const holder = this.getExtensionHolder_(extensionId,  false);
    this.insertExtensionScriptIfNeeded_(extensionId, holder);
    return this.waitFor_(holder);
  }
preloadExtension ( extensionId ) { if ( extensionId == 'amp-embed' ) { extensionId = 'amp-ad' ; } const holder = this . getExtensionHolder_ ( extensionId , false ) ; this . insertExtensionScriptIfNeeded_ ( extensionId , holder ) ; return this . waitFor_ ( holder ) ; }
Returns the promise that will be resolved when the extension has been
 loaded.
Returns the promise that will be resolved when the extension has been loaded .
/* auto */