Enable a11y audit for chrome://print and fix failing tests.

chrome/browser/resources/print_preview/previewarea/margin_control.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.
 
 cr.define('print_preview', function() {
   'use strict';
 
   /**
    * Draggable control for setting a page margin.
    * @param {!print_preview.ticket_items.CustomMargins.Orientation} orientation
@@ skipping 169 matching lines @@
      * @param {!print_preview.Size} pageSize New size of the document's pages.
      */
     setPageSize: function(pageSize) {
       this.pageSize_ = pageSize;
       this.setPositionInPts(this.positionInPts_);
     },
 
     /** @param {boolean} isVisible Whether the margin control is visible. */
     setIsVisible: function(isVisible) {
       this.getElement().classList.toggle('invisible', !isVisible);
+      this.getElement().setAttribute('aria-hidden', !isVisible);
     },
 
     /** @return {boolean} Whether the margin control is in an error state. */
     getIsInError: function() {
       return this.isInError_;
     },
 
     /**
      * @param {boolean} isInError Whether the margin control is in an error
      *     state.
@@ skipping 117 matching lines @@
       this.marginLineEl_ = this.getElement().getElementsByClassName(
           MarginControl.Classes_.LINE)[0];
     },
 
     /** @override */
     enterDocument: function() {
       print_preview.Component.prototype.enterDocument.call(this);
       this.tracker.add(
           this.getElement(), 'mousedown', this.onMouseDown_.bind(this));
       this.tracker.add(
-          this.getElement(),
-          'webkitTransitionEnd',
-          this.onWebkitTransitionEnd_.bind(this));
-      this.tracker.add(
           this.textbox_, 'input', this.onTextboxInput_.bind(this));
       this.tracker.add(
           this.textbox_, 'keydown', this.onTextboxKeyDown_.bind(this));
       this.tracker.add(
           this.textbox_, 'focus', this.setIsFocused_.bind(this, true));
       this.tracker.add(this.textbox_, 'blur', this.onTexboxBlur_.bind(this));
     },
 
     /** @override */
     exitDocument: function() {
@@ skipping 23 matching lines @@
         this.mouseStartPositionInPixels_ =
             new print_preview.Coordinate2d(event.x, event.y);
         this.marginStartPositionInPixels_ = new print_preview.Coordinate2d(
             this.getElement().offsetLeft, this.getElement().offsetTop);
         this.setIsInError(false);
         cr.dispatchSimpleEvent(this, MarginControl.EventType.DRAG_START);
       }
     },
 
     /**
-     * Called when opacity CSS transition ends.
-     * @private
-     */
-    onWebkitTransitionEnd_: function(event) {

[Dan Beam, 2014/10/15 21:37:31]

not lgtm, add back before you land
https://code.google.com/p/chromium/codesearch#chromium/src/chrome/browser/res...

[hcarmona, 2014/10/17 01:35:53]

Acknowledged.

-      if (event.propertyName != 'opacity')
-        return;
-      var elStyle = window.getComputedStyle(this.getElement());
-      var opacity = parseInt(elStyle.getPropertyValue('opacity'), 10);
-      this.textbox_.setAttribute('aria-hidden', opacity == 0);
-    },
-
-    /**
      * Called when textbox content changes. Starts text change timeout.
      * @private
      */
     onTextboxInput_: function(event) {
       if (this.textTimeout_) {
         clearTimeout(this.textTimeout_);
         this.textTimeout_ = null;
       }
       this.textTimeout_ = setTimeout(
           this.onTextboxTimeout_.bind(this), MarginControl.TEXTBOX_TIMEOUT_);
@@ skipping 36 matching lines @@
       this.setIsFocused_(false);
       cr.dispatchSimpleEvent(this, MarginControl.EventType.TEXT_CHANGE);
     }
   };
 
   // Export
   return {
     MarginControl: MarginControl
   };
 });