Oilpan: move mutation observers to the Oilpan heap.

Source/core/dom/NodeRareData.h

Index: Source/core/dom/NodeRareData.h
diff --git a/Source/core/dom/NodeRareData.h b/Source/core/dom/NodeRareData.h
index 1de8431b2ca1938f08551e6374836a2b86ded554..9e8d139fc429999ded697e7fe333a6627fee6d2f 100644
--- a/Source/core/dom/NodeRareData.h
+++ b/Source/core/dom/NodeRareData.h
@@ -29,6 +29,7 @@
 #include "core/dom/QualifiedName.h"
 #include "core/dom/TagCollection.h"
 #include "core/page/Page.h"
+#include "platform/heap/Handle.h"
 #include "wtf/HashSet.h"
 #include "wtf/OwnPtr.h"
 #include "wtf/PassOwnPtr.h"
@@ -209,13 +210,23 @@ private:
     TagCollectionCacheNS m_tagCollectionCacheNS;
 };
 
-class NodeMutationObserverData {
-    WTF_MAKE_NONCOPYABLE(NodeMutationObserverData); WTF_MAKE_FAST_ALLOCATED;
+class NodeMutationObserverData FINAL : public NoBaseWillBeGarbageCollected<NodeMutationObserverData> {
+    WTF_MAKE_NONCOPYABLE(NodeMutationObserverData);
+    WTF_MAKE_FAST_ALLOCATED_WILL_BE_REMOVED;
 public:
-    Vector<OwnPtr<MutationObserverRegistration> > registry;
-    HashSet<MutationObserverRegistration*> transientRegistry;
+    WillBeHeapVector<OwnPtrWillBeMember<MutationObserverRegistration> > registry;
+    WillBeHeapHashSet<RawPtrWillBeMember<MutationObserverRegistration> > transientRegistry;

[Erik Corry, 2014/04/22 12:46:55]

I suppose these raw pointers were only cycle-breaking raw pointers, not weak
pointers?

[haraken, 2014/04/22 13:03:07]

It would depend on how you see these pointers. In a sense that these pointers
are just breaking cycles, they are weak poniters. On the other hand, in a sense
that these pointers are always explicitly cleared, they can be viewed as strong
pointers (Even if we make these pointers weak, there is no chance for GC to
clear out the weak pointers).

(Either is fine with me.)

[sof, 2014/04/22 13:05:29]

Ownership with these transients raw pointers lie with the registry of some child
Node (see Node::notifyMutationObserversNodeWillDetach()). We don't have ref
counting over these, so I'm not sure what that makes them.

 
-    static PassOwnPtr<NodeMutationObserverData> create() { return adoptPtr(new NodeMutationObserverData); }
+    static PassOwnPtrWillBeRawPtr<NodeMutationObserverData> create()
+    {
+        return adoptPtrWillBeNoop(new NodeMutationObserverData);
+    }
+
+    void trace(Visitor* visitor)
+    {
+        visitor->trace(registry);
+        visitor->trace(transientRegistry);
+    }
 
 private:
     NodeMutationObserverData() { }
@@ -224,7 +235,12 @@ private:
 class NodeRareData : public NodeRareDataBase {
     WTF_MAKE_NONCOPYABLE(NodeRareData); WTF_MAKE_FAST_ALLOCATED;
 public:
-    static PassOwnPtr<NodeRareData> create(RenderObject* renderer) { return adoptPtr(new NodeRareData(renderer)); }
+    static PassOwnPtr<NodeRareData> create(RenderObject* renderer)
+    {
+        return adoptPtr(new NodeRareData(renderer));
+    }
+
+    void dispose();
 
     void clearNodeLists() { m_nodeLists.clear(); }
     NodeListsNodeData* nodeLists() const { return m_nodeLists.get(); }
@@ -278,7 +294,7 @@ protected:
 
 private:
     OwnPtr<NodeListsNodeData> m_nodeLists;
-    OwnPtr<NodeMutationObserverData> m_mutationObserverData;
+    OwnPtrWillBePersistent<NodeMutationObserverData> m_mutationObserverData;
 
     unsigned m_connectedFrameCount : ConnectedFrameCountBits;
     unsigned m_elementFlags : NumberOfElementFlags;