Oilpan: make DOMWindowProperty a GC mixin.

Source/modules/donottrack/NavigatorDoNotTrack.cpp

 /*
  * Copyright (C) 2013 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 24 matching lines @@
 #include "core/frame/Navigator.h"
 #include "core/loader/FrameLoaderClient.h"
 
 namespace blink {
 
 NavigatorDoNotTrack::NavigatorDoNotTrack(LocalFrame* frame)
     : DOMWindowProperty(frame)
 {
 }
 
-NavigatorDoNotTrack::~NavigatorDoNotTrack()
+DEFINE_EMPTY_DESTRUCTOR_WILL_BE_REMOVED(NavigatorDoNotTrack);
+
+void NavigatorDoNotTrack::trace(Visitor* visitor)
 {
+    WillBeHeapSupplement<Navigator>::trace(visitor);
+    DOMWindowProperty::trace(visitor);
 }
 
 const char* NavigatorDoNotTrack::supplementName()
 {
     return "NavigatorDoNotTrack";
 }
 
 NavigatorDoNotTrack& NavigatorDoNotTrack::from(Navigator& navigator)
 {
     NavigatorDoNotTrack* supplement = static_cast<NavigatorDoNotTrack*>(WillBeHeapSupplement<Navigator>::from(navigator, supplementName()));
@@ skipping 10 matching lines @@
 }
 
 String NavigatorDoNotTrack::doNotTrack()
 {
     if (!frame() || !frame()->loader().client())
         return String();
     return frame()->loader().client()->doNotTrackValue();
 }
 
 } // namespace blink