SELECT element: Refer to m_lastOnChangeOption in HTMLSelectElement::optionIndexToBeShown().

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 1077 matching lines @@
     // 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 || !multiple() || flags & DeselectOtherOptions)
             setActiveSelectionAnchor(element);
         if (!m_activeSelectionEnd || !multiple() || 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())
         m_popup->updateFromElement(PopupMenu::BySelectionChange);
 
     scrollToSelection();
     setNeedsValidityCheck();
 
     if (usesMenuList()) {
-        if (flags & DispatchInputAndChangeEvent)
-            dispatchInputAndChangeEventForMenuList();
-        else
-            m_lastOnChangeOption = element;
+        if (shouldDispatchEvents) {
+            dispatchInputEvent();
+            dispatchFormControlChangeEvent();
+        }
         if (LayoutObject* layoutObject = this->layoutObject()) {
-            // Need to check usesMenuList() again because
-            // dispatchInputAndChangeEventForMenuList() might change the status.
+            // Need to check usesMenuList() again because event handlers might
+            // change the status.
             if (usesMenuList()) {
                 // didSetSelectedIndex() is O(N) because of optionToListIndex.
                 toLayoutMenuList(layoutObject)->didSetSelectedIndex(optionIndex);
             }
         }
     }
 
     notifyFormStateChanged();
 }
 
@@ skipping 111 matching lines @@
             toHTMLOptionElement(item)->setSelectedState(false);
     }
 
     // The saved state should have at least one value and an index.
     ASSERT(state.valueSize() >= 2);
     if (!multiple()) {
         size_t index = state[1].toUInt();
         if (index < itemsSize && isHTMLOptionElement(items[index]) && toHTMLOptionElement(items[index])->value() == state[0]) {
             toHTMLOptionElement(items[index])->setSelectedState(true);
             toHTMLOptionElement(items[index])->setDirty(true);
+            m_lastOnChangeOption = toHTMLOptionElement(items[index]);
         } else {
             size_t foundIndex = searchOptionsForValue(state[0], 0, itemsSize);
             if (foundIndex != kNotFound) {
                 toHTMLOptionElement(items[foundIndex])->setSelectedState(true);
                 toHTMLOptionElement(items[foundIndex])->setDirty(true);
+                m_lastOnChangeOption = toHTMLOptionElement(items[foundIndex]);
             }
         }
     } else {
         size_t startIndex = 0;
         for (size_t i = 0; i < state.valueSize(); i+= 2) {
             const String& value = state[i];
             const size_t index = state[i + 1].toUInt();
             if (index < itemsSize && isHTMLOptionElement(items[index]) && toHTMLOptionElement(items[index])->value() == value) {
                 toHTMLOptionElement(items[index])->setSelectedState(true);
                 toHTMLOptionElement(items[index])->setDirty(true);
@@ skipping 710 matching lines @@
 {
     m_indexToSelectOnCancel = listIndex;
     if (layoutObject())
         layoutObject()->updateFromElement();
 }
 
 int HTMLSelectElement::optionIndexToBeShown() const
 {
     if (m_indexToSelectOnCancel >= 0)
         return listToOptionIndex(m_indexToSelectOnCancel);
+    // TODO(tkent): HTMLOptionElement::index() is O(N). This function should
+    // return HTMLOptionElement*.
     if (m_suggestedOption)
         return m_suggestedOption->index();
-    return selectedIndex();
+    int optionIndex = m_lastOnChangeOption ? m_lastOnChangeOption->index() : -1;
+    DCHECK_EQ(optionIndex, selectedIndex());
+    return optionIndex;
 }
 
 void HTMLSelectElement::valueChanged(unsigned listIndex)
 {
     // Check to ensure a page navigation has not occurred while the popup was
     // up.
     Document& doc = document();
     if (&doc != doc.frame()->document())
         return;
 
@@ skipping 135 matching lines @@
 }
 
 void HTMLSelectElement::didMutateSubtree()
 {
     DCHECK(popupIsVisible());
     DCHECK(m_popup);
     m_popup->updateFromElement(PopupMenu::ByDOMChange);
 }
 
 } // namespace blink