Oilpan: Prepare moving AXObject to heap

Source/modules/accessibility/AXObjectCacheImpl.h

Index: Source/modules/accessibility/AXObjectCacheImpl.h
diff --git a/Source/modules/accessibility/AXObjectCacheImpl.h b/Source/modules/accessibility/AXObjectCacheImpl.h
index 7899f4993dda4e6cad6535f401d05d6f09614b00..d2bf3359fec84c98de63e5d37a982fe3632ff669 100644
--- a/Source/modules/accessibility/AXObjectCacheImpl.h
+++ b/Source/modules/accessibility/AXObjectCacheImpl.h
@@ -55,15 +55,19 @@ struct TextMarkerData {
 
 // This class should only be used from inside the accessibility directory.
 class MODULES_EXPORT AXObjectCacheImpl : public AXObjectCache {
-    WTF_MAKE_NONCOPYABLE(AXObjectCacheImpl); WTF_MAKE_FAST_ALLOCATED(AXObjectCacheImpl);
+    WTF_MAKE_NONCOPYABLE(AXObjectCacheImpl);
+    WTF_MAKE_FAST_ALLOCATED_WILL_BE_REMOVED(AXObjectCacheImpl);
 public:
-    static AXObjectCache* create(Document&);
+    static PassOwnPtrWillBeRawPtr<AXObjectCache> create(Document&);
 
     explicit AXObjectCacheImpl(Document&);
     ~AXObjectCacheImpl();
+    DECLARE_VIRTUAL_TRACE();
 
     AXObject* focusedUIElementForPage(const Page*);
 
+    virtual void dispose() override;
+
     virtual void selectionChanged(Node*) override;
     virtual void childrenChanged(Node*) override;
     virtual void childrenChanged(LayoutObject*) override;
@@ -134,7 +138,11 @@ public:
 
     AXObject* firstAccessibleObjectFromNode(const Node*);
 
+#if ENABLE(OILPAN)
+    void remove(AXObject*);

[dmazzoni, 2015/04/28 06:53:25]

Can we make this change for the non-oilpan compile just so there aren't two code
paths?

[keishi, 2015/05/28 06:49:19]

Done.

+#else
     void remove(AXID);
+#endif
     void remove(AbstractInlineTextBox*);
 
     void childrenChanged(AXObject*);
@@ -149,7 +157,9 @@ public:
     bool accessibilityEnabled();
     bool inlineTextBoxAccessibilityEnabled();
 
+#if !ENABLE(OILPAN)
     void removeAXID(AXObject*);
+#endif
     bool isIDinUse(AXID id) const { return m_idsInUse.contains(id); }
 
     AXID platformGenerateAXID() const;
@@ -172,24 +182,35 @@ protected:
     void removeNodeForUse(Node* n) { m_textMarkerNodes.remove(n); }
     bool isNodeInUse(Node* n) { return m_textMarkerNodes.contains(n); }
 
-    PassRefPtr<AXObject> createFromRenderer(LayoutObject*);
-    PassRefPtr<AXObject> createFromNode(Node*);
-    PassRefPtr<AXObject> createFromInlineTextBox(AbstractInlineTextBox*);
+    PassRefPtrWillBeRawPtr<AXObject> createFromRenderer(LayoutObject*);
+    PassRefPtrWillBeRawPtr<AXObject> createFromNode(Node*);
+    PassRefPtrWillBeRawPtr<AXObject> createFromInlineTextBox(AbstractInlineTextBox*);
 
 private:
+    void removeAXID(AXID);
+
     Document& m_document;
+
+#if ENABLE(OILPAN)
+    HeapHashMap<AXID, WeakMember<AXObject>> m_objects;
+    HeapHashMap<LayoutObject*, Member<AXObject>> m_layoutObjectMapping;
+    HeapHashMap<WeakMember<Widget>, Member<AXObject>> m_widgetObjectMapping;
+    HeapHashMap<WeakMember<Node>, Member<AXObject>> m_nodeObjectMapping;

[dmazzoni, 2015/04/28 06:53:25]

I'm worried about WeakMember<Node> here. We rely on getting a call to
AXObjectCache::remove(Node*) from Node::willBeDeletedFromDocument currently.
With this change, it looks like that call won't happen, so we'll end up with an
entry in the HashMap with a null key and the AXObject won't detach itself.

[keishi, 2015/05/28 06:49:19]

HeapHashMap with WeakMember entries will automatically be removed by weak
processing.
However, in this case we need to call AXNodeObject::detach for the removed nodes
so I am doing custom weak processing.
I've registered AXObjectCacheImpl::clearWeakMembers as a weak processing
callback using registerWeakMembers.
AXObjectCacheImpl::clearWeakMembers scans the map for unmarked Nodes, and calls
remove(Node*) so they are removed from the map and so AXNodeObject::detach is
called.

+    HeapHashMap<AbstractInlineTextBox*, Member<AXObject>> m_inlineTextBoxObjectMapping;
+#else
     HashMap<AXID, RefPtr<AXObject>> m_objects;
     HashMap<LayoutObject*, AXID> m_layoutObjectMapping;
     HashMap<Widget*, AXID> m_widgetObjectMapping;
     HashMap<Node*, AXID> m_nodeObjectMapping;
     HashMap<AbstractInlineTextBox*, AXID> m_inlineTextBoxObjectMapping;
-    HashSet<Node*> m_textMarkerNodes;
+#endif
+    WillBeHeapHashSet<RawPtrWillBeWeakMember<Node>> m_textMarkerNodes;
     int m_modificationCount;
 
     HashSet<AXID> m_idsInUse;
 
     Timer<AXObjectCacheImpl> m_notificationPostTimer;
-    Vector<pair<RefPtr<AXObject>, AXNotification>> m_notificationsToPost;
+    WillBeHeapVector<pair<RefPtrWillBeMember<AXObject>, AXNotification>> m_notificationsToPost;
     void notificationPostTimerFired(Timer<AXObjectCacheImpl>*);
 
     AXObject* focusedImageMapUIElement(HTMLAreaElement*);