Add Autofill preview support for <select> input fields

Source/core/html/HTMLSelectElement.cpp

Index: Source/core/html/HTMLSelectElement.cpp
diff --git a/Source/core/html/HTMLSelectElement.cpp b/Source/core/html/HTMLSelectElement.cpp
index 710aff5591e54959d330111276ae8f5207eb4bde..9c49e329d4818f6546c585ab29025b8e7f8fa67a 100644
--- a/Source/core/html/HTMLSelectElement.cpp
+++ b/Source/core/html/HTMLSelectElement.cpp
@@ -253,6 +253,35 @@ void HTMLSelectElement::setValue(const String &value)
     setSelectedIndex(-1);
 }
 
+String HTMLSelectElement::suggestedValue() const
+{
+    return m_suggestedValue;
+}
+
+void HTMLSelectElement::setSuggestedValue(const String& value)
+{
+    m_suggestedValue = value;
+
+    if (value.isNull()) {
+        setSuggestedIndex(-1);
+        return;
+    }
+
+    const Vector<HTMLElement*>& items = listItems();
+    unsigned optionIndex = 0;
+    for (unsigned i = 0; i < items.size(); i++) {
+        if (items[i]->hasLocalName(optionTag)) {
+            if (toHTMLOptionElement(items[i])->value() == value) {
+                setSuggestedIndex(optionIndex);
+                return;
+            }
+            optionIndex++;
+        }
+    }
+
+    setSuggestedIndex(-1);
+}
+
 bool HTMLSelectElement::isPresentationAttribute(const QualifiedName& name) const
 {
     if (name == alignAttr) {
@@ -792,6 +821,24 @@ void HTMLSelectElement::setSelectedIndex(int index)
     selectOption(index, DeselectOtherOptions);
 }
 
+int HTMLSelectElement::suggestedIndex() const
+{
+    return m_suggestedIndex;
+}
+
+void HTMLSelectElement::setSuggestedIndex(int suggestedIndex)
+{
+    m_suggestedIndex = suggestedIndex;
+
+    if (RenderObject* renderer = this->renderer())  {
+        renderer->updateFromElement();
+        if (renderer->isListBox())
+            toRenderListBox(renderer)->scrollToRevealElementAtListIndex(suggestedIndex);
+    }
+
+    setNeedsValidityCheck();
+}
+
 void HTMLSelectElement::optionSelectionStateChanged(HTMLOptionElement* option, bool optionIsSelected)
 {
     ASSERT(option->ownerSelectElement() == this);