extensions/amp-story/1.0/amp-story-system-layer.js
/**
   * Reacts to has audio state updates, determining if the story has a global
   * audio track playing, or if any page has audio.
   * @param {boolean} hasAudio
   * @private
   */
Reacts to has audio state updates, determining if the story has a global
audio track playing, or if any page has audio.
@param {boolean} hasAudio
@private
Reacts to has audio state updates determining if the story has a global audio track playing or if any page has audio . @param { boolean } hasAudio @private
onStoryHasAudioStateUpdate_(hasAudio) {
    this.vsync_.mutate(() => {
      this.getShadowRoot().classList.toggle(
        'i-amphtml-story-has-audio',
        hasAudio
      );
    });
  }
onStoryHasAudioStateUpdate_ ( hasAudio ) { this . vsync_ . mutate ( ( ) => { this . getShadowRoot ( ) . classList . toggle ( 'i-amphtml-story-has-audio' , hasAudio ) ; } ) ; }
Reacts to has audio state updates, determining if the story has a global
 audio track playing, or if any page has audio.
Reacts to has audio state updates determining if the story has a global audio track playing or if any page has audio .