Refactor the Heap into ThreadHeap to prepare for per thread heaps

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

Index: third_party/WebKit/Source/platform/heap/PersistentNode.h
diff --git a/third_party/WebKit/Source/platform/heap/PersistentNode.h b/third_party/WebKit/Source/platform/heap/PersistentNode.h
index f6ebddbfeca63fea2fd166576e6028f3a785378b..62338d88f1e56535b675b13f63711e121abb27bc 100644
--- a/third_party/WebKit/Source/platform/heap/PersistentNode.h
+++ b/third_party/WebKit/Source/platform/heap/PersistentNode.h
@@ -143,7 +143,7 @@ public:
         --m_persistentCount;
 #endif
     }
-    void tracePersistentNodes(Visitor*);
+    void tracePersistentNodes(Visitor*, bool (*shouldTrace)(Visitor*, PersistentNode*) = nullptr);

[haraken, 2016/01/28 15:52:50]

Use typedef for the function signature.

[keishi, 2016/02/29 06:02:33]

Done.

     int numberOfPersistents();
 
 private:
@@ -177,11 +177,13 @@ public:
     void tracePersistentNodes(Visitor* visitor)
     {
         MutexLocker lock(m_mutex);
-        m_persistentRegion->tracePersistentNodes(visitor);
+        m_persistentRegion->tracePersistentNodes(visitor, CrossThreadPersistentRegion::shouldTracePersistentNode);
     }
 
     void prepareForThreadStateTermination(ThreadState*);
 
+    static bool shouldTracePersistentNode(Visitor*, PersistentNode*);
+
 private:
     // We don't make CrossThreadPersistentRegion inherit from PersistentRegion
     // because we don't want to virtualize performance-sensitive methods