Oilpan: Prepare to move form control ua shadow elements to Oilpan heap.

Source/core/html/shadow/SpinButtonElement.h

 /*
  * Copyright (C) 2006, 2008, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2010 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
@@ skipping 26 matching lines @@
 public:
     enum UpDownState {
         Indeterminate, // Hovered, but the event is not handled.
         Down,
         Up,
     };
     enum EventDispatch {
         EventDispatchAllowed,
         EventDispatchDisallowed,
     };
-    class SpinButtonOwner {
+    class SpinButtonOwner : public WillBeGarbageCollectedMixin {
     public:
         virtual ~SpinButtonOwner() { }
         virtual void focusAndSelectSpinButtonOwner() = 0;
         virtual bool shouldSpinButtonRespondToMouseEvents() = 0;
         virtual bool shouldSpinButtonRespondToWheelEvents() = 0;
         virtual void spinButtonDidReleaseMouseCapture(EventDispatch) = 0;
         virtual void spinButtonStepDown() = 0;
         virtual void spinButtonStepUp() = 0;
     };
 
     // The owner of SpinButtonElement must call removeSpinButtonOwner
     // because SpinButtonElement can be outlive SpinButtonOwner
     // implementation, e.g. during event handling.
     static PassRefPtr<SpinButtonElement> create(Document&, SpinButtonOwner&);
     UpDownState upDownState() const { return m_upDownState; }
     void releaseCapture(EventDispatch = EventDispatchAllowed);
-    void removeSpinButtonOwner() { m_spinButtonOwner = 0; }
+    void removeSpinButtonOwner() { m_spinButtonOwner = nullptr; }
 
     void step(int amount);
 
     virtual bool willRespondToMouseMoveEvents() OVERRIDE;
     virtual bool willRespondToMouseClickEvents() OVERRIDE;
 
     void forwardEvent(Event*);
 
+    virtual void trace(Visitor*) OVERRIDE;
+
 private:
     SpinButtonElement(Document&, SpinButtonOwner&);
 
     virtual void detach(const AttachContext&) OVERRIDE;
     virtual bool isSpinButtonElement() const OVERRIDE { return true; }
     virtual bool isDisabledFormControl() const OVERRIDE { return shadowHost() && shadowHost()->isDisabledFormControl(); }
     virtual bool matchesReadOnlyPseudoClass() const OVERRIDE;
     virtual bool matchesReadWritePseudoClass() const OVERRIDE;
     virtual void defaultEventHandler(Event*) OVERRIDE;
     virtual void willOpenPopup() OVERRIDE;
     void doStepAction(int);
     void startRepeatingTimer();
     void stopRepeatingTimer();
     void repeatingTimerFired(Timer<SpinButtonElement>*);
     virtual void setHovered(bool = true) OVERRIDE;
     bool shouldRespondToMouseEvents();
     virtual bool isMouseFocusable() const OVERRIDE { return false; }
 
-    SpinButtonOwner* m_spinButtonOwner;
+    RawPtrWillBeMember<SpinButtonOwner> m_spinButtonOwner;
     bool m_capturing;
     UpDownState m_upDownState;
     UpDownState m_pressStartingState;
     Timer<SpinButtonElement> m_repeatingTimer;
 };
 
 DEFINE_TYPE_CASTS(SpinButtonElement, Node, node, toElement(node)->isSpinButtonElement(), toElement(node).isSpinButtonElement());
 
 } // namespace
 
 #endif