Oilpan: Make the Node hierarchy RefCountedGarbageCollected instead of TreeShared.

Source/core/dom/Node.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 256 matching lines @@
 #endif
 
     if (hasRareData())
         clearRareData();
 
     RELEASE_ASSERT(!renderer());
 
 #if !ENABLE(OILPAN)
     if (!isContainerNode())
         willBeDeletedFromDocument();
-#endif
 
     if (m_previous)
         m_previous->setNextSibling(0);
     if (m_next)
         m_next->setPreviousSibling(0);
 
-#if !ENABLE(OILPAN)
     if (m_treeScope)
         m_treeScope->guardDeref();
 #endif
 
     InspectorCounters::decrementCounter(InspectorCounters::NodeCounter);
 
     if (getFlag(HasWeakReferencesFlag))
         WeakNodeMap::notifyNodeDestroyed(this);
 }
 
@@ skipping 2073 matching lines @@
     return isContentEditable(UserSelectAllIsAlwaysNonEditable) || hasEventListeners(EventTypeNames::mouseup) || hasEventListeners(EventTypeNames::mousedown) || hasEventListeners(EventTypeNames::click) || hasEventListeners(EventTypeNames::DOMActivate);
 }
 
 bool Node::willRespondToTouchEvents()
 {
     if (isDisabledFormControl(this))
         return false;
     return hasEventListeners(EventTypeNames::touchstart) || hasEventListeners(EventTypeNames::touchmove) || hasEventListeners(EventTypeNames::touchcancel) || hasEventListeners(EventTypeNames::touchend);
 }
 
+#if !ENABLE(OILPAN)
 // This is here for inlining
-#if ENABLE(OILPAN)
-inline void TreeScope::removedLastRefToScope()
-{
-    dispose();

[haraken, 2014/05/06 15:59:42]

I agree that we're going toward a right direction, but might need to keep in
mind that this change can cause some web-exposed behavior change. Before this
CL, Document was disposed when the last ref to the TreeScope is gone. After this
CL, Document is disposed when the Document is detached. This means that the
point where the Document is disposed becomes earlier than before, which can
cause web-exposed behavior change.

[Mads Ager (chromium), 2014/05/07 12:13:16]

Yes, I completely agree and I did think about that. We need to continue working
on making the dispose call that is currently happening in detach unnecessary.

-}
-#else
 inline void TreeScope::removedLastRefToScope()
 {
     ASSERT_WITH_SECURITY_IMPLICATION(!deletionHasBegun());
     if (m_guardRefCount) {
         // If removing a child removes the last self-only ref, we don't
         // want the scope to be destructed until after
         // removeDetachedChildren returns, so we guard ourselves with an
         // extra self-only ref.
         guardRef();
         dispose();
 #if !ASSERT_DISABLED
         // We need to do this right now since guardDeref() can delete this.
         rootNode().m_inRemovedLastRefFunction = false;
 #endif
         guardDeref();
     } else {
 #if !ASSERT_DISABLED
         rootNode().m_inRemovedLastRefFunction = false;
 #endif
 #if SECURITY_ASSERT_ENABLED
         beginDeletion();
 #endif
         delete this;
     }
 }
-#endif
 
 // It's important not to inline removedLastRef, because we don't want to inline the code to
 // delete a Node at each deref call site.
 void Node::removedLastRef()
 {
     // An explicit check for Document here is better than a virtual function since it is
     // faster for non-Document nodes, and because the call to removedLastRef that is inlined
     // at all deref call sites is smaller if it's a non-virtual function.
     if (isTreeScope()) {
         treeScope().removedLastRefToScope();
         return;
     }
 
-#if !ENABLE(OILPAN)
 #if SECURITY_ASSERT_ENABLED
     m_deletionHasBegun = true;
 #endif
     delete this;
+}
 #endif
-}
 
 unsigned Node::connectedSubframeCount() const
 {
     return hasRareData() ? rareData()->connectedSubframeCount() : 0;
 }
 
 void Node::incrementConnectedSubframeCount(unsigned amount)
 {
     ASSERT(isContainerNode());
     ensureRareData().incrementConnectedSubframeCount(amount);
@@ skipping 123 matching lines @@
     ASSERT(isHTMLElement() || isSVGElement());
     setFlag(CustomElementFlag);
     setFlag(newState == Upgraded, CustomElementUpgradedFlag);
 
     if (oldState == NotCustomElement || newState == Upgraded)
         setNeedsStyleRecalc(SubtreeStyleChange); // :unresolved has changed
 }
 
 void Node::trace(Visitor* visitor)
 {
+    visitor->trace(m_parentOrShadowHostNode);
+    visitor->trace(m_previous);
+    visitor->trace(m_next);
     visitor->trace(m_treeScope);
 }
 
 } // namespace WebCore
 
 #ifndef NDEBUG
 
 void showNode(const WebCore::Node* node)
 {
     if (node)
         node->showNode("");
 }
 
 void showTree(const WebCore::Node* node)
 {
     if (node)
         node->showTreeForThis();
 }
 
 void showNodePath(const WebCore::Node* node)
 {
     if (node)
         node->showNodePathForThis();
 }
 
 #endif