Oilpan: turn StyleResourceLoader into a traced part object.

Source/core/css/resolver/StyleResourceLoader.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  *
  */
 
 #ifndef StyleResourceLoader_h
 #define StyleResourceLoader_h
 
-#include "wtf/OwnPtr.h"
-#include "wtf/PassRefPtr.h"
+#include "platform/heap/Handle.h"
+#include "wtf/Forward.h"
 
 namespace blink {
 
 class ElementStyleResources;
 class Document;
 class LayoutStyle;
 class RenderStyle;
 class ShapeValue;
 class StyleImage;
 class StylePendingImage;
 
 // Manages loading of resources, requested by the stylesheets.
 // Expects the same lifetime as StyleResolver, because
 // it expects Document to never change.
-class StyleResourceLoader {
-WTF_MAKE_NONCOPYABLE(StyleResourceLoader);
+class StyleResourceLoader final {
+    WTF_MAKE_NONCOPYABLE(StyleResourceLoader);
+    DISALLOW_ALLOCATION();
 public:
     explicit StyleResourceLoader(Document*);
 
     void loadPendingResources(LayoutStyle*, ElementStyleResources&);
 
+    DECLARE_TRACE();
+
 private:
     void loadPendingSVGDocuments(LayoutStyle*, ElementStyleResources&);
 
     PassRefPtr<StyleImage> loadPendingImage(StylePendingImage*, float deviceScaleFactor);
     void loadPendingImages(LayoutStyle*, ElementStyleResources&);
     void loadPendingShapeImage(LayoutStyle*, ShapeValue*, float deviceScaleFactor);
 
-    Document* m_document;
+    RawPtrWillBeMember<Document> m_document;
 };
 
 } // namespace blink
 
 #endif // StyleResourceLoader_h