Make ChromeVox cursor robust to deleted nodes

chrome/browser/resources/chromeos/chromevox/cvox2/background/background.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 The entry point for all ChromeVox2 related code for the
  * background page.
  */
 
 goog.provide('Background');
@@ skipping 732 matching lines @@
         description['Reproduction Steps'] = '%0a1.%0a2.%0a3.';
         for (var key in description)
           url += key + ':%20' + description[key] + '%0a';
         chrome.tabs.create({url: url});
         return false;
       default:
         return true;
     }
 
     if (pred) {
-      var node = AutomationUtil.findNextNode(
-          current.getBound(dir).node, dir, pred, {skipInitialAncestry: true});
+      var bound = current.getBound(dir).node;
+      if (bound) {
+        var node = AutomationUtil.findNextNode(
+            bound, dir, pred, {skipInitialAncestry: true});
+        if (node) {
+          node = AutomationUtil.findNodePre(
+              node, dir, AutomationPredicate.element) || node;
+        }
 
-      if (node) {
-        node = AutomationUtil.findNodePre(
-            node, dir, AutomationPredicate.element) || node;
-      }
-
-      if (node) {
-        current = cursors.Range.fromNode(node);
-      } else {
-        if (predErrorMsg) {
-          cvox.ChromeVox.tts.speak(Msgs.getMsg(predErrorMsg),
-                                   cvox.QueueMode.FLUSH);
+        if (node) {
+          current = cursors.Range.fromNode(node);
+        } else {
+          if (predErrorMsg) {
+            cvox.ChromeVox.tts.speak(Msgs.getMsg(predErrorMsg),
+                                     cvox.QueueMode.FLUSH);
+          }
+          return false;
         }
-        return false;
       }
     }
 
     if (current)
       this.navigateToRange_(current);
 
     return false;
   },
 
   /**
@@ skipping 345 matching lines @@
     return glob.replace(/[.+^$(){}|[\]\\]/g, '\\$&')
         .replace(/\*/g, '.*')
         .replace(/\?/g, '.');
   }).join('|') + ')$');
 };
 
 /** @type {Background} */
 global.backgroundObj = new Background();
 
 });  // goog.scope