Oilpan: Make the Node hierarchy RefCountedGarbageCollected instead of TreeShared.

Source/core/dom/shadow/ElementShadow.cpp

 /*
  * Copyright (C) 2012 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Neither the name of Google Inc. nor the names of its
@@ skipping 117 matching lines @@
 }
 
 ElementShadow::ElementShadow()
     : m_needsDistributionRecalc(false)
     , m_needsSelectFeatureSet(false)
 {
 }
 
 ElementShadow::~ElementShadow()
 {
+#if !ENABLE(OILPAN)
     removeDetachedShadowRoots();
+#endif
 }
 
 ShadowRoot& ElementShadow::addShadowRoot(Element& shadowHost, ShadowRoot::ShadowRootType type)
 {
     RefPtr<ShadowRoot> shadowRoot = ShadowRoot::create(shadowHost.document(), type);
 
     if (type == ShadowRoot::AuthorShadowRoot && (!youngestShadowRoot() || youngestShadowRoot()->type() == ShadowRoot::UserAgentShadowRoot))
         shadowHost.willAddFirstAuthorShadowRoot();
 
     for (ShadowRoot* root = youngestShadowRoot(); root; root = root->olderShadowRoot())
@@ skipping 12 matching lines @@
     return *m_shadowRoots.head();
 }
 
 void ElementShadow::removeDetachedShadowRoots()
 {
     // Dont protect this ref count.
     Element* shadowHost = host();
     ASSERT(shadowHost);
 
     while (RefPtr<ShadowRoot> oldRoot = m_shadowRoots.head()) {
         InspectorInstrumentation::willPopShadowRoot(shadowHost, oldRoot.get());

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

Add a FIXME and mention if this is OK to remove or not.

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

I'll file a bug report to investigate and reach out to the devtools team for
this.

         shadowHost->document().removeFocusedElementOfSubtree(oldRoot.get());
         m_shadowRoots.removeHead();
         oldRoot->setParentOrShadowHostNode(0);
         oldRoot->setParentTreeScope(shadowHost->document());
         oldRoot->setPrev(0);
         oldRoot->setNext(0);
     }
 
 }
 
@@ skipping 161 matching lines @@
 }
 
 void ElementShadow::clearDistribution()
 {
     m_nodeToInsertionPoints.clear();
 
     for (ShadowRoot* root = youngestShadowRoot(); root; root = root->olderShadowRoot())
         root->setShadowInsertionPointOfYoungerShadowRoot(nullptr);
 }
 
+void ElementShadow::trace(Visitor* visitor)
+{
+    // Shadow roots are linked with previous and next pointers which are traced.
+    // It is therefore enough to trace one of the shadow roots here and the
+    // rest will be traced from there.
+    visitor->trace(m_shadowRoots.head());
+}
+
 } // namespace