Fix regression in Mac AX live region support

content/browser/accessibility/browser_accessibility_manager_mac.mm

Index: content/browser/accessibility/browser_accessibility_manager_mac.mm
diff --git a/content/browser/accessibility/browser_accessibility_manager_mac.mm b/content/browser/accessibility/browser_accessibility_manager_mac.mm
index ab9272392479b2da4255aec822b141de874ad4b2..1361164af50e99f5959471dad1462b147ec576d6 100644
--- a/content/browser/accessibility/browser_accessibility_manager_mac.mm
+++ b/content/browser/accessibility/browser_accessibility_manager_mac.mm
@@ -150,6 +150,8 @@ void BrowserAccessibilityManagerMac::OnAtomicUpdateFinished(
 
   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;