Printe Preview: add 'More/less options' button and make non-essential sections collapsible

chrome/browser/resources/print_preview/print_preview_animations.js

 // Copyright (c) 2012 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.
 
 // Counter used to give webkit animations unique names.
 var animationCounter = 0;
 
 var animationEventTracker_ = new EventTracker();
 
 function addAnimation(code) {
@@ skipping 25 matching lines @@
 /**
  * Fades in an element. Used for both printing options and error messages
  * appearing underneath the textfields.
  * @param {HTMLElement} el The element to be faded in.
  */
 function fadeInElement(el) {
   if (el.classList.contains('visible'))
     return;
   el.classList.remove('closing');
   el.hidden = false;
+  el.setAttribute('aria-hidden', 'false');
   el.style.height = 'auto';
   var height = el.offsetHeight;
   el.style.height = height + 'px';
   var animName = addAnimation(getFadeInAnimationCode(height));
   animationEventTracker_.add(
       el, 'webkitAnimationEnd', onFadeInAnimationEnd.bind(el), false);
   el.style.webkitAnimationName = animName;
   el.classList.add('visible');
 }
 
 /**
  * Fades out an element. Used for both printing options and error messages
  * appearing underneath the textfields.
  * @param {HTMLElement} el The element to be faded out.
  */
 function fadeOutElement(el) {
   if (!el.classList.contains('visible'))
     return;
   fadeInAnimationCleanup(el);
   el.style.height = 'auto';
   var height = el.offsetHeight;
   el.style.height = height + 'px';
   el.offsetHeight;  // Should force an update of the computed style.
   animationEventTracker_.add(
       el, 'webkitTransitionEnd', onFadeOutTransitionEnd.bind(el), false);
   el.classList.add('closing');
   el.classList.remove('visible');
+  el.setAttribute('aria-hidden', 'true');
 }
 
 /**
  * Executes when a fade out animation ends.
  * @param {WebkitTransitionEvent} event The event that triggered this listener.
  * @this {HTMLElement} The element where the transition occurred.
  */
 function onFadeOutTransitionEnd(event) {
   if (event.propertyName != 'height')
     return;
@@ skipping 86 matching lines @@
     while (el.childNodes.length > 0)
       div.appendChild(el.firstChild);
     el.appendChild(div);
   }
 
   div.className = '';
   div.classList.add('collapsible');
   for (var i = 0; i < classes.length; i++)
     div.classList.add(classes[i]);
 }