Oilpan: add transition types to track interface objects.

Source/core/html/track/vtt/VTTRegionList.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:
  * 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 40 matching lines @@
         return 0;
 
     for (size_t i = 0; i < m_list.size(); ++i) {
         if (m_list[i]->id() == id)
             return m_list[i].get();
     }
 
     return 0;
 }
 
-void VTTRegionList::add(PassRefPtr<VTTRegion> region)
+void VTTRegionList::add(PassRefPtrWillBeRawPtr<VTTRegion> region)
 {
     m_list.append(region);
 }
 
 bool VTTRegionList::remove(VTTRegion* region)
 {
     size_t index = m_list.find(region);
     if (index == kNotFound)
         return false;
 
     m_list.remove(index);
     return true;
 }
 
-void VTTRegionList::clear()
+void VTTRegionList::trace(Visitor* visitor)
 {
-    m_list.clear();
+    visitor->trace(m_list);
 }
 
 } // namespace WebCore