Oilpan: Make the Node hierarchy RefCountedGarbageCollected instead of TreeShared.

Source/core/dom/StyleEngine.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
@@ skipping 72 matching lines @@
         {
         }
     };
 
     friend class IgnoringPendingStylesheet;
 
     static PassOwnPtrWillBeRawPtr<StyleEngine> create(Document& document) { return adoptPtrWillBeNoop(new StyleEngine(document)); }
 
     ~StyleEngine();
 
+#if !ENABLE(OILPAN)
     void detachFromDocument();
+#endif
 
     const WillBeHeapVector<RefPtrWillBeMember<StyleSheet> >& styleSheetsForStyleSheetList(TreeScope&);
     const WillBeHeapVector<RefPtrWillBeMember<CSSStyleSheet> >& activeAuthorStyleSheets() const;
 
     const WillBeHeapVector<RefPtrWillBeMember<CSSStyleSheet> >& documentAuthorStyleSheets() const { return m_authorStyleSheets; }
     const WillBeHeapVector<RefPtrWillBeMember<CSSStyleSheet> >& injectedAuthorStyleSheets() const;
 
     const WillBeHeapVector<RefPtrWillBeMember<StyleSheet> > activeStyleSheetsForInspector() const;
 
     void modifiedStyleSheet(StyleSheet*);
@@ skipping 99 matching lines @@
     Document* master();
 
     typedef ListHashSet<TreeScope*, 16> TreeScopeSet;
     static void insertTreeScopeInDocumentOrder(TreeScopeSet&, TreeScope*);
     void clearMediaQueryRuleSetOnTreeScopeStyleSheets(TreeScopeSet treeScopes);
 
     void createResolver();
 
     static PassRefPtrWillBeRawPtr<CSSStyleSheet> parseSheet(Element*, const String& text, TextPosition startPosition, bool createdByParser);
 
     Document& m_document;

[Erik Corry, 2014/05/05 12:47:01]

This doesn't keep the document alive?

[Mads Ager (chromium), 2014/05/05 12:52:39]

The StyleEngine is owned (OwnPtr) by the document. When we move the StyleEngine
to the heap we should make this a Member.

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

The StyleEngine is already on the heap :)

Before this CL, Document::m_styleEngine was a persistent handle, and thus this
Document& was no problem. However, after this CL, Document::m_styleEngine
becomes a Member and thus Document& becomes a problem. So I think you need to
change this to a Member in this CL.

Probably we should seriously consider replacing a reference back to a raw
pointer, and replace it with RawPtrWillBeMember.

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

Yes, I'll do that. I think we will end up replacing a lot of references with
pointers again. References are really hard for us to deal with. You cannot make
good transition types for them.

     bool m_isMaster;
 
     // Track the number of currently loading top-level stylesheets needed for rendering.
     // Sheets loaded using the @import directive are not included in this count.
     // We use this count of pending sheets to detect when we can begin attaching
     // elements and when it is safe to execute scripts.
     int m_pendingStylesheets;
 
     mutable WillBeHeapVector<RefPtrWillBeMember<CSSStyleSheet> > m_injectedAuthorStyleSheets;
     mutable bool m_injectedStyleSheetCacheValid;
@@ skipping 24 matching lines @@
 
     RefPtrWillBeMember<CSSFontSelector> m_fontSelector;
 
     WillBeHeapHashMap<AtomicString, RawPtrWillBeMember<StyleSheetContents> > m_textToSheetCache;
     WillBeHeapHashMap<RawPtrWillBeMember<StyleSheetContents>, AtomicString> m_sheetToTextCache;
 };
 
 }
 
 #endif