Oilpan: Prepare moving DateTimeChooser to Oilpan

Source/platform/DateTimeChooser.h

 /*
  * 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 15 matching lines @@
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef DateTimeChooser_h
 #define DateTimeChooser_h
 
 #include "platform/PlatformExport.h"
 #include "platform/geometry/IntRect.h"
+#include "platform/heap/Handle.h"
 #include "wtf/RefCounted.h"
 #include "wtf/text/WTFString.h"
 
 namespace WebCore {
 
 struct DateTimeSuggestion {
     double value;
     String localizedValue;
     String label;
 };
@@ skipping 10 matching lines @@
     double doubleValue;
     Vector<DateTimeSuggestion> suggestions;
     double minimum;
     double maximum;
     double step;
     double stepBase;
     bool required;
     bool isAnchorElementRTL;
 };
 
-// For pickers like color pickers and date pickers.
-class PLATFORM_EXPORT DateTimeChooser : public RefCounted<DateTimeChooser> {
+class PLATFORM_EXPORT DateTimeChooser : public RefCountedWillBeGarbageCollectedFinalized<DateTimeChooser> {
 public:
     virtual ~DateTimeChooser();
 
     virtual void endChooser() = 0;
+    virtual void trace(Visitor*) { }
 };
 
 } // namespace WebCore
 #endif // DateTimeChooser_h