Ensure WebView notifies desktop automation on creation, destruction, and change

chrome/browser/resources/chromeos/chromevox/cvox2/background/automation_util.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 ChromeVox utilities for the automation extension API.
  */
 
 goog.provide('AutomationUtil');
 goog.provide('AutomationUtil.Dir');
@@ skipping 70 matching lines @@
  * Find the next node in the given direction that is either an immediate sibling
  * or a sibling of an ancestor.
  * @param {AutomationNode} cur Node to start search from.
  * @param {Dir} dir
  * @return {AutomationNode}
  */
 AutomationUtil.findNextSubtree = function(cur, dir) {
   while (cur) {
     var next = dir == Dir.BACKWARD ?
         cur.previousSibling : cur.nextSibling;
+    if (!AutomationUtil.isInSameTree(cur, next))
+      return null;
     if (next)
       return next;
+    if (!AutomationUtil.isInSameTree(cur, cur.parent))
+      return null;
     cur = cur.parent;
   }
 };
 
 /**
  * Find the next node in the given direction in depth first order.
  * @param {AutomationNode} cur Node to begin the search from.
  * @param {Dir} dir
  * @param {AutomationPredicate.Unary} pred A predicate to apply
  *     to a candidate node.
@@ skipping 54 matching lines @@
 /**
  * Returns an array containing ancestors of node starting at root down to node.
  * @param {!AutomationNode} node
  * @return {!Array.<AutomationNode>}
  */
 AutomationUtil.getAncestors = function(node) {
   var ret = [];
   var candidate = node;
   while (candidate) {
     ret.push(candidate);
+
+    if (!AutomationUtil.isInSameTree(candidate, candidate.parent))
+      break;
+
     candidate = candidate.parent;
   }
   return ret.reverse();
 };
 
 /**
  * Gets the first index where the two input arrays differ. Returns -1 if they
  * do not.
  * @param {!Array.<AutomationNode>} ancestorsA
  * @param {!Array.<AutomationNode>} ancestorsB
@@ skipping 42 matching lines @@
   var divB = ancestorsB[divergence];
 
   // One of the nodes is an ancestor of the other. Don't distinguish and just
   // consider it Dir.FORWARD.
   if (!divA || !divB || divA.parent === nodeB || divB.parent === nodeA)
     return Dir.FORWARD;
 
   return divA.indexInParent <= divB.indexInParent ? Dir.FORWARD : Dir.BACKWARD;
 };
 
+/**
+ * Determines whether the two given nodes come from the same tree source.
+ * @param {AutomationNode} a
+ * @param {AutomationNode} b
+ * @return {boolean}
+ */
+AutomationUtil.isInSameTree = function(a, b) {
+  if (!a || !b)
+    return true;
+
+  return a.root === b.root;
+};
+
 });  // goog.scope