SELECT element: Do not update popup menu content by touching selectedIndex

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.
@@ skipping 963 matching lines @@
   setRecalcListItems();
   m_lastOnChangeSelection.clear();
 }
 
 // TODO(tkent): This function is not efficient.  It contains multiple O(N)
 // operations. crbug.com/577989.
 void HTMLSelectElement::selectOption(HTMLOptionElement* element,
                                      SelectOptionFlags flags) {
   TRACE_EVENT0("blink", "HTMLSelectElement::selectOption");
 
+  bool shouldUpdatePopup = false;
+
   // selectedOption() is O(N).
   if (isAutofilled() && selectedOption() != element)
     setAutofilled(false);
 
   if (element) {
+    if (!element->selected())
+      shouldUpdatePopup = true;
     element->setSelectedState(true);
     if (flags & MakeOptionDirty)
       element->setDirty(true);
   }
 
   // deselectItemsWithoutValidation() is O(N).
   if (flags & DeselectOtherOptions)
-    deselectItemsWithoutValidation(element);
+    shouldUpdatePopup |= deselectItemsWithoutValidation(element);
 
   // We should update active selection after finishing OPTION state change
   // because setActiveSelectionAnchorIndex() stores OPTION's selection state.
   if (element) {
     // setActiveSelectionAnchor is O(N).
     if (!m_activeSelectionAnchor || !isMultiple() ||
         flags & DeselectOtherOptions)
       setActiveSelectionAnchor(element);
     if (!m_activeSelectionEnd || !isMultiple() || flags & DeselectOtherOptions)
       setActiveSelectionEnd(element);
   }
 
   // Need to update m_lastOnChangeOption before
   // LayoutMenuList::updateFromElement.
   bool shouldDispatchEvents = false;
   if (usesMenuList()) {
     shouldDispatchEvents = (flags & DispatchInputAndChangeEvent) &&
                            m_lastOnChangeOption != element;
     m_lastOnChangeOption = element;
   }
 
   // For the menu list case, this is what makes the selected element appear.
   if (LayoutObject* layoutObject = this->layoutObject())
     layoutObject->updateFromElement();
   // PopupMenu::updateFromElement() posts an O(N) task.
-  if (popupIsVisible())
+  if (popupIsVisible() && shouldUpdatePopup)
     m_popup->updateFromElement(PopupMenu::BySelectionChange);
 
   scrollToSelection();
   setNeedsValidityCheck();
 
   if (usesMenuList()) {
     if (shouldDispatchEvents) {
       dispatchInputEvent();
       dispatchChangeEvent();
     }
@@ skipping 32 matching lines @@
   // made.  This matches other browsers' behavior.
   if (usesMenuList())
     dispatchInputAndChangeEventForMenuList();
   m_lastOnChangeSelection.clear();
   if (popupIsVisible())
     hidePopup();
   HTMLFormControlElementWithState::dispatchBlurEvent(newFocusedElement, type,
                                                      sourceCapabilities);
 }
 
-void HTMLSelectElement::deselectItemsWithoutValidation(
+// Returns true if selection state of any OPTIONs is changed.
+bool HTMLSelectElement::deselectItemsWithoutValidation(
     HTMLOptionElement* excludeElement) {
   if (!isMultiple() && usesMenuList() && m_lastOnChangeOption &&
       m_lastOnChangeOption != excludeElement) {
     m_lastOnChangeOption->setSelectedState(false);
-    return;
+    return true;
   }
+  bool didUpdateSelection = false;
   for (const auto& option : optionList()) {
-    if (option != excludeElement)
+    if (option != excludeElement) {
+      if (option->selected())
+        didUpdateSelection = true;
       option->setSelectedState(false);
+    }
   }
+  return didUpdateSelection;
 }
 
 FormControlState HTMLSelectElement::saveFormControlState() const {
   const ListItems& items = listItems();
   size_t length = items.size();
   FormControlState state;
   for (unsigned i = 0; i < length; ++i) {
     if (!isHTMLOptionElement(*items[i]))
       continue;
     HTMLOptionElement* option = toHTMLOptionElement(items[i]);
@@ skipping 925 matching lines @@
   m_popupUpdater = nullptr;
 }
 
 void HTMLSelectElement::didMutateSubtree() {
   DCHECK(popupIsVisible());
   DCHECK(m_popup);
   m_popup->updateFromElement(PopupMenu::ByDOMChange);
 }
 
 }  // namespace blink