Initial support for accessible text fields and focus tracking in ARC++

chrome/browser/resources/chromeos/chromevox/cvox2/background/cursors.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.
 
 /**
  * @fileoverview Classes related to cursors that point to and select parts of
  * the automation tree.
  */
 
 goog.provide('cursors.Cursor');
@@ skipping 124 matching lines @@
 
   /**
    * Returns the node. If the node is invalid since the last time it
    * was accessed, moves the cursor to the nearest valid ancestor first.
    * @return {AutomationNode}
    */
   get node() {
     for (var i = 0; i < this.ancestry_.length; i++) {
       var firstValidNode = this.ancestry_[i];
       if (firstValidNode != null && firstValidNode.role !== undefined &&
-          firstValidNode.root !== undefined) {
+          firstValidNode.root != undefined) {

[hidehiko, 2017/03/21 03:43:23]

nit: looks unnecessary change? (Or any reasons to relax the condition...?)

[David Tseng, 2017/03/21 16:41:16]

It actually is. There are some cases, particularly in text fields, where the
text field node is detached and its parent is set to null (not undefined).

[hidehiko, 2017/03/21 22:00:43]

firstValidNode.root can be null, I think it's nice to comment (or explicitly
check either null or undefined), for future maintenance.

         return firstValidNode;
       }
       // If we have to walk up to an ancestor, reset the index to NODE_INDEX.
       this.index_ = cursors.NODE_INDEX;
     }
     return null;
   },
 
   /**
    * @return {number}
@@ skipping 13 matching lines @@
     if (!adjustedNode)
       return null;
 
     // Make no adjustments if we're within editable content.
     if (adjustedNode.state.editable)
       return adjustedNode;
 
     // Selections over line break nodes are broken.
     var parent = adjustedNode.parent;
     var grandparent = parent && parent.parent;
-    if (parent.role == RoleType.LINE_BREAK) {
+    if (parent && parent.role == RoleType.LINE_BREAK) {
       adjustedNode = grandparent;
-    } else if (grandparent.role == RoleType.LINE_BREAK) {
+    } else if (grandparent && grandparent.role == RoleType.LINE_BREAK) {
       adjustedNode = grandparent.parent;
     } else if (this.index_ == cursors.NODE_INDEX ||
         adjustedNode.role == RoleType.INLINE_TEXT_BOX ||
         adjustedNode.nameFrom != chrome.automation.NameFromType.CONTENTS) {
       // A node offset or unselectable character offset.
       adjustedNode = parent;
     } else {
       // A character offset into content.
       adjustedNode =
           adjustedNode.find({role: RoleType.STATIC_TEXT}) || adjustedNode;
@@ skipping 495 matching lines @@
   /**
    * Returns whether this range has valid start and end cursors.
    * @return {boolean}
    */
   isValid: function() {
     return this.start.isValid() && this.end.isValid();
   }
 };
 
 });  // goog.scope