SELECT popup: Do not update popup content for arbitrary attribute change.

third_party/WebKit/Source/core/html/HTMLSelectElement.cpp

 /*
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2009, 2010, 2011 Apple Inc. All rights reserved.
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
@@ skipping 2014 matching lines @@
     }
 
     Member<HTMLSelectElement> m_select;
     Member<MutationObserver> m_observer;
 };
 
 HTMLSelectElement::PopupUpdater::PopupUpdater(HTMLSelectElement& select)
     : m_select(select)
 {
     m_observer = MutationObserver::create(this);
+    Vector<String> filter;
+    filter.reserveCapacity(4);
+    // Observe only attributes which affect popup content.
+    filter.append(String("disabled"));
+    filter.append(String("label"));
+    filter.append(String("selected"));
+    filter.append(String("value"));
     MutationObserverInit init;
     init.setAttributes(true);
+    init.setAttributeFilter(filter);
     init.setCharacterData(true);
     init.setChildList(true);
     init.setSubtree(true);
     m_observer->observe(&select, init, ASSERT_NO_EXCEPTION);
 }
 
 DEFINE_TRACE(HTMLSelectElement::PopupUpdater)
 {
     visitor->trace(m_select);
     visitor->trace(m_observer);
@@ skipping 15 matching lines @@
 }
 
 void HTMLSelectElement::didMutateSubtree()
 {
     DCHECK(popupIsVisible());
     DCHECK(m_popup);
     m_popup->updateFromElement(PopupMenu::ByDOMChange);
 }
 
 } // namespace blink