Add checks for per thread heap

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

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MarkingVisitorImpl_h
 #define MarkingVisitorImpl_h
 
 #include "platform/heap/Heap.h"
 #include "platform/heap/ThreadState.h"
 #include "platform/heap/Visitor.h"
@@ skipping 23 matching lines @@
         // release builds will crash in the following header->isMarked()
         // because all the entries of the orphaned arenas are zapped.
         ASSERT(!pageFromObject(objectPointer)->orphaned());
 
         if (header->isMarked())
             return;
 
         ASSERT(ThreadState::current()->isInGC());
         ASSERT(toDerived()->getMarkingMode() != Visitor::WeakProcessing);
 
+        // A GC should only mark the objects that belong in its heap.
+        DCHECK(&pageFromObject(objectPointer)->arena()->getThreadState()->heap() == &toDerived()->heap());
+
         header->mark();
 
         if (callback)
             toDerived()->heap().pushTraceCallback(const_cast<void*>(objectPointer), callback);
     }
 
     inline void mark(const void* objectPointer, TraceCallback callback)
     {
         if (!objectPointer)
             return;
@@ skipping 69 matching lines @@
 private:
     static void markNoTracingCallback(Visitor* visitor, void* object)
     {
         visitor->markNoTracing(object);
     }
 };
 
 } // namespace blink
 
 #endif