Files app: Compile custom elements.

ui/file_manager/audio_player/elements/control_panel.js

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+/**
+ * @typedef {?{

[oka, 2016/12/26 11:38:38]

nit: Can you remove ? here and add ? to @type {AriaLabels} ?

[fukino, 2016/12/26 11:44:43]

This is a common pattern for typedefs of record types.
The header comment of chrome_extensions.js have more details.
https://codesearch.chromium.org/chromium/src/third_party/closure_compiler/ext...

+ *   mute: string,
+ *   next: string,
+ *   pause: string,
+ *   play: string,
+ *   playList: string,
+ *   previous: string,
+ *   repeat: string,
+ *   seekSlider: string,
+ *   shuffle: string,
+ *   unmute: string,
+ *   volume: string,
+ *   volumeSlider: string,
+ * }}
+ */
+var AriaLabels;
+
 (function() {
   'use strict';
 
   /**
    * Moves |target| element above |anchor| element, in order to match the
    * bottom lines.
    * @param {HTMLElement} target Target element.
    * @param {HTMLElement} anchor Anchor element.
    */
   function matchBottomLine(target, anchor) {
@@ skipping 95 matching lines @@
        * Whether the knob of time slider is being dragged.
        */
       dragging: {
         type: Boolean,
         value: false,
         notify: true
       },
 
       /**
        * Dictionary which contains aria-labels for each controls.
+       * @type {AriaLabels}
        */
       ariaLabels: {
         type: Object,
         observer: 'ariaLabelsChanged_'
       }
     },
 
     /**
      * Initializes an element. This method is called automatically when the
      * element is ready.
@@ skipping 171 matching lines @@
       this.$.next.setAttribute('aria-label', ariaLabels.next);
       this.$.volumeButton.setAttribute('aria-label', ariaLabels.volume);
       this.$.playList.setAttribute('aria-label', ariaLabels.playList);
       this.$.timeSlider.setAttribute('aria-label', ariaLabels.seekSlider);
       this.$.volumeButton.setAttribute('aria-label',
           this.volume !== 0 ? ariaLabels.mute : ariaLabels.unmute);
       this.$.volumeSlider.setAttribute('aria-label', ariaLabels.volumeSlider);
     },
   });
 })();  // Anonymous closure