Fix regression in Mac AX live region support

content/browser/accessibility/browser_accessibility_manager_mac.mm

 // 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.
 
 #include "content/browser/accessibility/browser_accessibility_manager_mac.h"
 
 #import "base/logging.h"
 #import "content/browser/accessibility/browser_accessibility_cocoa.h"
 #import "content/browser/accessibility/browser_accessibility_mac.h"
 #include "content/common/accessibility_messages.h"
@@ skipping 132 matching lines @@
   DCHECK(native_node);
   NSAccessibilityPostNotification(native_node, event_id);
 }
 
 void BrowserAccessibilityManagerMac::OnAtomicUpdateFinished(
     bool root_changed, const std::vector<ui::AXTreeDelegate::Change>& changes) {
   BrowserAccessibilityManager::OnAtomicUpdateFinished(root_changed, changes);
 
   bool created_live_region = false;
   for (size_t i = 0; i < changes.size(); ++i) {
+    if (changes[i].type != NODE_CREATED && changes[i].type != SUBTREE_CREATED)
+      continue;
     BrowserAccessibility* obj = GetFromAXNode(changes[i].node);
     if (obj && obj->HasStringAttribute(ui::AX_ATTR_LIVE_STATUS)) {
       created_live_region = true;
       break;
     }
   }
 
   if (!created_live_region)
     return;
 
   // This code is to work around a bug in VoiceOver, where a new live
   // region that gets added is ignored. VoiceOver seems to only scan the
   // page for live regions once. By recreating the NSAccessibility
   // object for the root of the tree, we force VoiceOver to clear out its
   // internal state and find newly-added live regions this time.
   BrowserAccessibilityMac* root =
       static_cast<BrowserAccessibilityMac*>(GetRoot());
   root->RecreateNativeObject();
   NotifyAccessibilityEvent(ui::AX_EVENT_CHILDREN_CHANGED, root);
 }
 
 }  // namespace content