Oilpan: catch some self-referential leaks (main thread.)

Source/platform/heap/PersistentNode.h

 // Copyright 2015 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 PersistentNode_h
 #define PersistentNode_h
 
 #include "platform/PlatformExport.h"
 #include "platform/heap/ThreadState.h"
 #include "wtf/Assertions.h"
@@ skipping 64 matching lines @@
     bool isUnused() const
     {
         return !m_trace;
     }
 
     void* self() const
     {
         return m_self;
     }
 
+    TraceCallback traceCallback() const
+    {
+        return m_trace;
+    }
+
 private:
     // If this PersistentNode is in use:
     //   - m_self points to the corresponding Persistent handle.
     //   - m_trace points to the trace method.
     // If this PersistentNode is freed:
     //   - m_self points to the next freed PersistentNode.
     //   - m_trace is nullptr.
     void* m_self;
     TraceCallback m_trace;
 };
@@ skipping 42 matching lines @@
         ASSERT(m_persistentCount > 0);
         persistentNode->setFreeListNext(m_freeListHead);
         m_freeListHead = persistentNode;
 #if ENABLE(ASSERT)
         --m_persistentCount;
 #endif
     }
     void tracePersistentNodes(Visitor*);
     int numberOfPersistents();
 
+#ifndef NDEBUG
+    void dumpLivePersistents();
+#endif
+
 private:
     friend CrossThreadPersistentRegion;
 
     void ensurePersistentNodeSlots(void*, TraceCallback);
 
     PersistentNode* m_freeListHead;
     PersistentNodeSlots* m_slots;
 #if ENABLE(ASSERT)
     int m_persistentCount;
 #endif
@@ skipping 27 matching lines @@
     // We don't make CrossThreadPersistentRegion inherit from PersistentRegion
     // because we don't want to virtualize performance-sensitive methods
     // such as PersistentRegion::allocate/freePersistentNode.
     OwnPtr<PersistentRegion> m_persistentRegion;
     Mutex m_mutex;
 };
 
 } // namespace blink
 
 #endif