Compiling file_manager, part 2: remove all warnings not caused by Object.freeze()-like enums

ui/file_manager/file_manager/foreground/js/thumbnail_loader.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.
 
 'use strict';
 
 /**
  * Loads a thumbnail using provided url. In CANVAS mode, loaded images
  * are attached as <canvas> element, while in IMAGE mode as <img>.
  * <canvas> renders faster than <img>, however has bigger memory overhead.
@@ skipping 124 matching lines @@
 
 /**
  * Loads and attaches an image.
  *
  * @param {HTMLElement} box Container element.
  * @param {ThumbnailLoader.FillMode} fillMode Fill mode.
  * @param {ThumbnailLoader.OptimizationMode=} opt_optimizationMode Optimization
  *     for downloading thumbnails. By default optimizations are disabled.
  * @param {function(Image, Object)=} opt_onSuccess Success callback,
  *     accepts the image and the transform.
- * @param {function=} opt_onError Error callback.
- * @param {function=} opt_onGeneric Callback for generic image used.
+ * @param {function()=} opt_onError Error callback.
+ * @param {function()=} opt_onGeneric Callback for generic image used.
  */
 ThumbnailLoader.prototype.load = function(box, fillMode, opt_optimizationMode,
     opt_onSuccess, opt_onError, opt_onGeneric) {
   opt_optimizationMode = opt_optimizationMode ||
       ThumbnailLoader.OptimizationMode.NEVER_DISCARD;
 
   if (!this.thumbnailUrl_) {
     // Relevant CSS rules are in file_types.css.
     box.setAttribute('generic-thumbnail', this.mediaType_);
     if (opt_onGeneric) opt_onGeneric();
@@ skipping 258 matching lines @@
 
   function percent(fraction) {
     return (fraction * 100).toFixed(2) + '%';
   }
 
   img.style.width = percent(fractionX);
   img.style.height = percent(fractionY);
   img.style.left = percent((1 - fractionX) / 2);
   img.style.top = percent((1 - fractionY) / 2);
 };