SameThreadCheckedMember<>: verify same-thread usage of heap references.

third_party/WebKit/Source/platform/heap/Visitor.h

 /*
  * 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 33 matching lines @@
 
 template <typename T>
 class GarbageCollected;
 class HeapObjectHeader;
 class InlinedGlobalMarkingVisitor;
 template <typename T>
 class TraceTrait;
 class ThreadState;
 class Visitor;
 template <typename T>
+class SameThreadCheckedMember;
+template <typename T>
 class TraceWrapperMember;
 
 // The TraceMethodDelegate is used to convert a trace method for type T to a
 // TraceCallback.  This allows us to pass a type's trace method as a parameter
 // to the PersistentNode constructor. The PersistentNode constructor needs the
 // specific trace method due an issue with the Windows compiler which
 // instantiates even unused variables. This causes problems
 // in header files where we have only forward declarations of classes.
 template <typename T, void (T::*method)(Visitor*)>
 struct TraceMethodDelegate {
@@ skipping 92 matching lines @@
   template <typename T>
   void trace(const Member<T>& t) {
     mark(t.get());
   }
 
   template <typename T>
   void trace(const TraceWrapperMember<T>& t) {
     trace(*(static_cast<const Member<T>*>(&t)));
   }
 
+  template <typename T>
+  void trace(const SameThreadCheckedMember<T>& t) {
+    trace(*(static_cast<const Member<T>*>(&t)));
+  }
+
   // Fallback method used only when we need to trace raw pointers of T.
   // This is the case when a member is a union where we do not support members.
   template <typename T>
   void trace(const T* t) {
     mark(const_cast<T*>(t));
   }
   template <typename T>
   void trace(T* t) {
     mark(t);
   }
@@ skipping 213 matching lines @@
   static Visitor* fromHelper(VisitorHelper<Visitor>* helper) {
     return static_cast<Visitor*>(helper);
   }
 
   const MarkingMode m_markingMode;
 };
 
 }  // namespace blink
 
 #endif  // Visitor_h