Oilpan: move custom element objects to the heap.

Source/core/dom/custom/CustomElementUpgradeCandidateMap.h

Index: Source/core/dom/custom/CustomElementUpgradeCandidateMap.h
diff --git a/Source/core/dom/custom/CustomElementUpgradeCandidateMap.h b/Source/core/dom/custom/CustomElementUpgradeCandidateMap.h
index f68c50b65be76cea7412a881ba3ae7c256da5742..80e343be9b1f445c49ab3aad83a3c39c32e3bed5 100644
--- a/Source/core/dom/custom/CustomElementUpgradeCandidateMap.h
+++ b/Source/core/dom/custom/CustomElementUpgradeCandidateMap.h
@@ -42,31 +42,35 @@ namespace WebCore {
 
 class Element;
 
-class CustomElementUpgradeCandidateMap : CustomElementObserver {
+class CustomElementUpgradeCandidateMap FINAL : public CustomElementObserver {
     WTF_MAKE_NONCOPYABLE(CustomElementUpgradeCandidateMap);
 public:
-    CustomElementUpgradeCandidateMap() { }
-    ~CustomElementUpgradeCandidateMap();
+    static PassOwnPtrWillBeRawPtr<CustomElementUpgradeCandidateMap> create();
+    virtual ~CustomElementUpgradeCandidateMap();
 
     // API for CustomElementRegistrationContext to save and take candidates
 
-    typedef ListHashSet<Element*> ElementSet;
+    typedef WillBeHeapListHashSet<RawPtrWillBeMember<Element> > ElementSet;

[dominicc (has gone to gerrit), 2014/05/26 02:28:58]

Hmm... the idea of the CustomElementUpgradeCandidateMap is that it effectively
has a weak reference to the element. That is what the raw ptr and the
observation is about.

If this becomes a member, it looks like the CEUCM will keep the upgrade
candidates alive, which is not what we want. (It is allowable, but it could
regress performance. In particular, if an element never gets a definition, we're
going to hold onto a whole document etc. as a result, right?)

[sof, 2014/05/26 14:21:25]

Thanks, the weakness of that reference must stay the same with Oilpan. There was
a question whether or not it was effectively weak already, but not so.
I've added a test to verify non-leaking for that scenario (and verfied that it
leaked if the unresolved Element references were kept "strong".)

 
     void add(const CustomElementDescriptor&, Element*);
     void remove(Element*);
     ElementSet takeUpgradeCandidatesFor(const CustomElementDescriptor&);
 
+    virtual void trace(Visitor*) OVERRIDE;
+
 private:
+    CustomElementUpgradeCandidateMap() { }
+
     virtual void elementWasDestroyed(Element*) OVERRIDE;
     void removeCommon(Element*);
 
     virtual void elementDidFinishParsingChildren(Element*) OVERRIDE;
     void moveToEnd(Element*);
 
-    typedef HashMap<Element*, CustomElementDescriptor> UpgradeCandidateMap;
+    typedef WillBeHeapHashMap<RawPtrWillBeMember<Element>, CustomElementDescriptor> UpgradeCandidateMap;
     UpgradeCandidateMap m_upgradeCandidates;
 
-    typedef HashMap<CustomElementDescriptor, ElementSet> UnresolvedDefinitionMap;
+    typedef WillBeHeapHashMap<CustomElementDescriptor, ElementSet> UnresolvedDefinitionMap;
     UnresolvedDefinitionMap m_unresolvedDefinitions;
 };