ExternalPopupMenu should recreate its popup only if a SELECT subtree is updated

third_party/WebKit/Source/web/PopupMenuImpl.cpp

 // Copyright (c) 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.
 
 #include "web/PopupMenuImpl.h"
 
 #include "core/HTMLNames.h"
 #include "core/css/CSSFontSelector.h"
 #include "core/dom/ElementTraversal.h"
 #include "core/dom/ExecutionContextTask.h"
@@ skipping 458 matching lines @@
 }
 
 void PopupMenuImpl::updateFromElement()
 {
     if (m_needsUpdate)
         return;
     m_needsUpdate = true;
     ownerElement().document().postTask(BLINK_FROM_HERE, createSameThreadTask(&PopupMenuImpl::update, this));
 }
 
+void PopupMenuImpl::updateFromElementWithMutation()
+{
+    updateFromElement();
+}
+
 void PopupMenuImpl::update()
 {
     if (!m_popup || !m_ownerElement)
         return;
     ownerElement().document().updateLayoutTree();
     // disconnectClient() might have been called.
     if (!m_ownerElement)
         return;
     m_needsUpdate = false;
 
@@ skipping 31 matching lines @@
 
 void PopupMenuImpl::disconnectClient()
 {
     m_ownerElement = nullptr;
     // Cannot be done during finalization, so instead done when the
     // layout object is destroyed and disconnected.
     dispose();
 }
 
 } // namespace blink