Oilpan: Prepare moving DateTimeChooser to Oilpan

Source/core/html/forms/BaseChooserOnlyDateAndTimeInputType.h

Index: Source/core/html/forms/BaseChooserOnlyDateAndTimeInputType.h
diff --git a/Source/core/html/forms/BaseChooserOnlyDateAndTimeInputType.h b/Source/core/html/forms/BaseChooserOnlyDateAndTimeInputType.h
index 7b4af2f119fd9f40cb4754714f9e09ff16722e07..92e1764fb80f284cec2f7653a88e2f43e08de0c0 100644
--- a/Source/core/html/forms/BaseChooserOnlyDateAndTimeInputType.h
+++ b/Source/core/html/forms/BaseChooserOnlyDateAndTimeInputType.h
@@ -35,10 +35,13 @@
 namespace WebCore {
 
 class BaseChooserOnlyDateAndTimeInputType : public BaseDateAndTimeInputType, public DateTimeChooserClient {
+    WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(BaseChooserOnlyDateAndTimeInputType);
 protected:
-    BaseChooserOnlyDateAndTimeInputType(HTMLInputElement& element) : BaseDateAndTimeInputType(element) { }
+    explicit BaseChooserOnlyDateAndTimeInputType(HTMLInputElement& element) : BaseDateAndTimeInputType(element) { }
     virtual ~BaseChooserOnlyDateAndTimeInputType();
 
+    virtual void trace(Visitor*) OVERRIDE;
+
 private:
     void closeDateTimeChooser();
 
@@ -58,7 +61,7 @@ private:
     virtual void didChooseValue(double) OVERRIDE;
     virtual void didEndChooser() OVERRIDE;
 
-    RefPtr<DateTimeChooser> m_dateTimeChooser;
+    RefPtrWillBeMember<DateTimeChooser> m_dateTimeChooser;
 };
 
 }