Oilpan: Make the Node hierarchy RefCountedGarbageCollected instead of TreeShared.

Source/core/dom/TreeScope.cpp

 /*
  * Copyright (C) 2011 Google Inc. All Rights Reserved.
  * Copyright (C) 2012 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 69 matching lines @@
 #endif
     , m_idTargetObserverRegistry(IdTargetObserverRegistry::create())
 {
     m_rootNode.setTreeScope(this);
 }
 
 TreeScope::~TreeScope()
 {
 #if !ENABLE(OILPAN)
     ASSERT(!m_guardRefCount);
-#endif
     m_rootNode.setTreeScope(0);

[haraken, 2014/05/06 04:20:16]

You can remove this code because the root Node is guaranteed to exist in this
TreeScope and thus die together. Changing m_rootNode to a Member will make the
lifetime relationship clearer.

[Mads Ager (chromium), 2014/05/06 08:26:00]

Yes, it would. m_rootNode is a reference at this point but I'm tracing it. Let
me just make the reference a RawPtrWillBeMember. These references are not buying
us much and we end up taking their address explicitly a lot anyway.

 
-#if !ENABLE(OILPAN)
     if (m_selection) {
         m_selection->clearTreeScope();
         m_selection = nullptr;
     }
 
     if (m_parentTreeScope)
         m_parentTreeScope->guardDeref();
 #endif
 }
 
@@ skipping 227 matching lines @@
 
 bool TreeScope::applyAuthorStyles() const
 {
     return rootNode().isDocumentNode();
 }
 
 void TreeScope::adoptIfNeeded(Node& node)
 {
     ASSERT(this);
     ASSERT(!node.isDocumentNode());
+#if !ENABLE(OILPAN)
     ASSERT_WITH_SECURITY_IMPLICATION(!node.m_deletionHasBegun);
+#endif
     TreeScopeAdopter adopter(node, *this);
     if (adopter.needsScopeChange())
         adopter.execute();
 }
 
 static Element* focusedFrameOwnerElement(LocalFrame* focusedFrame, LocalFrame* currentFrame)
 {
     for (; focusedFrame; focusedFrame = focusedFrame->tree().parent()) {
         if (focusedFrame->tree().parent() == currentFrame)
             return focusedFrame->ownerElement();
@@ skipping 120 matching lines @@
     listTreeScopes(nodeB, treeScopesB);
 
     size_t indexA = treeScopesA.size();
     size_t indexB = treeScopesB.size();
 
     for (; indexA > 0 && indexB > 0 && treeScopesA[indexA - 1] == treeScopesB[indexB - 1]; --indexA, --indexB) { }
 
     return treeScopesA[indexA] == treeScopesB[indexB] ? treeScopesA[indexA] : 0;
 }
 
-#if SECURITY_ASSERT_ENABLED
+#if SECURITY_ASSERT_ENABLED && !ENABLE(OILPAN)
 bool TreeScope::deletionHasBegun()
 {
     return rootNode().m_deletionHasBegun;
 }
 
 void TreeScope::beginDeletion()
 {
     rootNode().m_deletionHasBegun = true;
 }
 #endif
 
+#if !ENABLE(OILPAN)
 int TreeScope::refCount() const
 {
     return rootNode().refCount();
 }
+#endif
 
 bool TreeScope::isInclusiveAncestorOf(const TreeScope& scope) const
 {
     for (const TreeScope* current = &scope; current; current = current->parentTreeScope()) {
         if (current == this)
             return true;
     }
     return false;
 }
 
@@ skipping 20 matching lines @@
         for (ShadowRoot* root = element->youngestShadowRoot(); root; root = root->olderShadowRoot())
             root->setNeedsStyleRecalcForViewportUnits();
         RenderStyle* style = element->renderStyle();
         if (style && style->hasViewportUnits())
             element->setNeedsStyleRecalc(LocalStyleChange);
     }
 }
 
 void TreeScope::trace(Visitor* visitor)
 {
+    visitor->trace(&m_rootNode);

[haraken, 2014/05/06 04:20:16]

This looks weird. Shall we change the reference back to a raw pointer and use
RawPtrWillBeMember in this CL?
 

[Mads Ager (chromium), 2014/05/06 08:26:00]

Yes, done.

+    visitor->trace(m_document);
     visitor->trace(m_parentTreeScope);
     visitor->trace(m_selection);
 }
 
 } // namespace WebCore