MD Downloads: update "expanded" (i.e. in progress) cards

chrome/browser/resources/md_downloads/item.js

 // Copyright 2015 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.
 
 cr.define('downloads', function() {
   var Item = Polymer({
     is: 'downloads-item',
 
     /**
      * @param {!downloads.ThrottledIconLoader} iconLoader
@@ skipping 62 matching lines @@
       this.$.content.classList.toggle('dangerous', this.isDangerous_);
 
       var description = dangerText || this.getStatusText_(data);
 
       // Status goes in the "tag" (next to the file name) if there's no file.
       this.ensureTextIs_(this.$.description, isActive ? description : '');
       this.ensureTextIs_(this.$.tag, isActive ? '' : description);
 
       /** @const */ var showProgress =
           isFinite(data.percent) && !this.isDangerous_;
-      this.$.progress.hidden = !showProgress;
+      this.$.content.classList.toggle('show-progress', showProgress);
 
       if (showProgress) {
         this.$.progress.indeterminate = data.percent < 0;
         this.$.progress.value = data.percent;
       }
 
       var disableRemove;
 
       if (this.isDangerous_) {
         this.isMalware_ =
@@ skipping 175 matching lines @@
     },
 
     /** @private */
     onShowClick_: function() {
       this.actionService_.show(this.id_);
     },
   });
 
   return {Item: Item};
 });