squash: remove unused prop, update comment

react/features/base/media/components/AbstractVideoTrack.js

  * @abstract
  */
 export default class AbstractVideoTrack extends Component {
-    /**
-     * Default values for AbstractVideoTrack component's properties.
-     *
-     * @static
-     */
-    static defaultProps = {
-        /**
-         * Dispatch an action when the video starts playing.
-         */
-        triggerOnPlayingUpdate: true
-    };
-
     /**
      * AbstractVideoTrack component's property types.
      *
     static propTypes = {
         dispatch: React.PropTypes.func,
 
-        /**
-         * Whether or not the store should be updated about the playing status
-         * of the video. Defaults to true. One use case for setting this prop
-         * to false is using multiple locals streams from the same video source,
-         * such as when previewing video. In those cases, the store may have no
-         * need to be updated about the existence or state of the stream.
-         */
-        triggerOnPlayingUpdate: React.PropTypes.bool,
-
         videoTrack: React.PropTypes.object,
 
         waitForVideoStarted: React.PropTypes.bool,
     _onVideoPlaying() {
         const videoTrack = this.props.videoTrack;
 
-        if (this.props.triggerOnPlayingUpdate
-            && videoTrack
+        if (videoTrack
             && !videoTrack.videoStarted) {
             this.props.dispatch(trackVideoStarted(videoTrack.jitsiTrack));
         }

react/features/base/media/components/web/VideoTrack.js

 import Video from './Video';
 
 /**
- * Component that renders a video element for a passed in video track.
+ * Component that renders a video element for a passed in video track and
+ * notifies the store when the video has started playing.
  *
  * @extends AbstractVideoTrack
  */

react/features/device-selection/components/VideoInputPreview.js

             <div className = { className }>
                 <Video
                     className = 'video-input-preview-display flipVideoX'
-                    triggerOnPlayingUpdate = { false }
                     videoTrack = {{ jitsiTrack: this.props.track }} />
                 <div className = 'video-input-preview-error'>
                     { error || '' }