Move the Widget hierarchy to the Oilpan heap.

Source/core/accessibility/AXObjectCache.cpp

 /*
  * Copyright (C) 2008, 2009, 2010 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 322 matching lines @@
 
 AXObject* AXObjectCache::getOrCreate(Widget* widget)
 {
     if (!widget)
         return 0;
 
     if (AXObject* obj = get(widget))
         return obj;
 
     RefPtr<AXObject> newObj = nullptr;
+    // FIXME: test for isScrollView() instead?
     if (widget->isFrameView())
         newObj = AXScrollView::create(toFrameView(widget));
     else if (widget->isScrollbar())
         newObj = AXScrollbar::create(toScrollbar(widget));
 
     // Will crash later if we have two objects for the same widget.
     ASSERT(!get(widget));
 
     // Catch the case if an (unsupported) widget type is used. Only FrameView and ScrollBar are supported now.
     ASSERT(newObj);
@@ skipping 219 matching lines @@
 // FIXME: Oilpan: Use a weak hashmap for this instead.
 void AXObjectCache::clearWeakMembers(Visitor* visitor)
 {
     Vector<Node*> deadNodes;
     for (HashMap<Node*, AXID>::iterator it = m_nodeObjectMapping.begin(); it != m_nodeObjectMapping.end(); ++it) {
         if (!visitor->isAlive(it->key))
             deadNodes.append(it->key);
     }
     for (unsigned i = 0; i < deadNodes.size(); ++i)
         remove(deadNodes[i]);
+
+    Vector<Widget*> deadWidgets;
+    for (HashMap<Widget*, AXID>::iterator it = m_widgetObjectMapping.begin(); it != m_widgetObjectMapping.end(); ++it) {
+        if (!visitor->isAlive(it->key))
+            deadWidgets.append(it->key);
+    }
+    for (unsigned i = 0; i < deadWidgets.size(); ++i)
+        remove(deadWidgets[i]);
 }
 
 AXID AXObjectCache::platformGenerateAXID() const
 {
     static AXID lastUsedID = 0;
 
     // Generate a new ID.
     AXID objID = lastUsedID;
     do {
         ++objID;
@@ skipping 448 matching lines @@
 void AXObjectCache::setCanvasObjectBounds(Element* element, const LayoutRect& rect)
 {
     AXObject* obj = getOrCreate(element);
     if (!obj)
         return;
 
     obj->setElementRect(rect);
 }
 
 } // namespace blink