Add autofill preview support for <month> input fields

Source/core/html/forms/BaseChooserOnlyDateAndTimeInputType.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
@@ skipping 46 matching lines @@
     m_dateTimeChooser = element().document().frameHost()->chrome().openDateTimeChooser(this, parameters);
 }
 
 void BaseChooserOnlyDateAndTimeInputType::createShadowSubtree()
 {
     DEFINE_STATIC_LOCAL(AtomicString, valueContainerPseudo, ("-webkit-date-and-time-value", AtomicString::ConstructFromLiteral));
 
     RefPtr<HTMLDivElement> valueContainer = HTMLDivElement::create(element().document());
     valueContainer->setShadowPseudoId(valueContainerPseudo);
     element().userAgentShadowRoot()->appendChild(valueContainer.get());
-    updateAppearance();
+    updateView();
 }
 
-void BaseChooserOnlyDateAndTimeInputType::updateAppearance()
+void BaseChooserOnlyDateAndTimeInputType::updateView()
 {
     Node* node = element().userAgentShadowRoot()->firstChild();
     if (!node || !node->isHTMLElement())
         return;
-    String displayValue = visibleValue();
+    String displayValue;
+    if (!element().suggestedValue().isNull())
+        displayValue = element().suggestedValue();
+    else
+        displayValue = visibleValue();
     if (displayValue.isEmpty()) {
         // Need to put something to keep text baseline.
         displayValue = " ";
     }
     toHTMLElement(node)->setInnerText(displayValue, ASSERT_NO_EXCEPTION);
 }
 
 void BaseChooserOnlyDateAndTimeInputType::setValue(const String& value, bool valueChanged, TextFieldEventBehavior eventBehavior)
 {
     BaseDateAndTimeInputType::setValue(value, valueChanged, eventBehavior);
     if (valueChanged)
-        updateAppearance();
+        updateView();
 }
 
 void BaseChooserOnlyDateAndTimeInputType::closePopupView()
 {
     closeDateTimeChooser();
 }
 
 void BaseChooserOnlyDateAndTimeInputType::didChooseValue(const String& value)
 {
     element().setValue(value, DispatchInputAndChangeEvent);
@@ skipping 35 matching lines @@
 }
 
 void BaseChooserOnlyDateAndTimeInputType::accessKeyAction(bool sendMouseEvents)
 {
     BaseDateAndTimeInputType::accessKeyAction(sendMouseEvents);
     BaseClickableWithKeyInputType::accessKeyAction(element(), sendMouseEvents);
 }
 
 }
 #endif