MD Bookmarks: Initial screenreader accessibility improvements

chrome/browser/resources/md_bookmarks/toast_manager.js

 // Copyright 2017 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.
 
 /**
  * @fileoverview Element which shows toasts.
  */
 cr.define('bookmarks', function() {
 
   var ToastManager = Polymer({
     is: 'bookmarks-toast-manager',
 
     properties: {
       duration: {
         type: Number,
         value: 0,
       },
 
       /** @private */
       open_: {
         type: Boolean,
-        reflectToAttribute: true,
+        observer: 'openChanged_',
+        value: false,
       },
 
       /** @private */
       showUndo_: Boolean,
     },
 
     /** @private {bookmarks.TimerProxy} */
     timerProxy_: new bookmarks.TimerProxy(),
 
     /** @private {number|null} */
     hideTimeoutId_: null,
 
     /** @override */
     attached: function() {
       assert(ToastManager.instance_ == null);
       ToastManager.instance_ = this;
+      Polymer.RenderStatus.afterNextRender(this, function() {
+        Polymer.IronA11yAnnouncer.requestAvailability();
+      });
     },
 
     /** @override */
     detached: function() {
       ToastManager.instance_ = null;
     },
 
     /**
      * @param {string} label The label to display inside the toast.
      * @param {boolean} showUndo Whether the undo button should be shown.
@@ skipping 26 matching lines @@
       this.showInternal_(showUndo);
     },
 
     /**
      * @param {boolean} showUndo Whether the undo button should be shown.
      * @private
      */
     showInternal_: function(showUndo) {
       this.open_ = true;
       this.showUndo_ = showUndo;
+      this.fire('iron-announce', {text: this.$.content.textContent});
 
       if (!this.duration)
         return;
 
       if (this.hideTimeoutId_ != null)
         this.timerProxy_.clearTimeout(this.hideTimeoutId_);
 
       this.hideTimeoutId_ = this.timerProxy_.setTimeout(function() {
-        this.open_ = false;
+        this.hide();
         this.hideTimeoutId_ = null;
       }.bind(this), this.duration);
     },
 
     hide: function() {
       this.open_ = false;
+      // Hide the undo button to prevent it from being accessed with tab.
+      this.showUndo_ = false;
     },
 
     /** @private */
     onUndoTap_: function() {
       // Will hide the toast.
       this.fire('command-undo');
     },
+
+    /** @private */
+    openChanged_: function() {
+      this.$.toast.setAttribute('aria-hidden', String(!this.open_));
+    },
   });
 
   /** @private {?bookmarks.ToastManager} */
   ToastManager.instance_ = null;
 
   /** @return {!bookmarks.ToastManager} */
   ToastManager.getInstance = function() {
     return assert(ToastManager.instance_);
   };
 
   return {
     ToastManager: ToastManager,
   };
 });