Change CSSImageValue's member variables from String to AtomicString

Source/core/css/CSSImageValue.h

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2008, 2012 Apple 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,
@@ skipping 20 matching lines @@
 class Document;
 class KURL;
 class StyleFetchedImage;
 class StyleImage;
 class LayoutObject;
 
 class CSSImageValue : public CSSValue {
 public:
     static PassRefPtrWillBeRawPtr<CSSImageValue> create(const KURL& url, StyleImage* image = 0)
     {
-        return adoptRefWillBeNoop(new CSSImageValue(url, url, image));
+        return create(url.string(), url, image);
     }
     static PassRefPtrWillBeRawPtr<CSSImageValue> create(const String& rawValue, const KURL& url, StyleImage* image = 0)
     {
+        return create(AtomicString(rawValue), url, image);
+    }
+    static PassRefPtrWillBeRawPtr<CSSImageValue> create(const AtomicString& rawValue, const KURL& url, StyleImage* image = 0)
+    {
         return adoptRefWillBeNoop(new CSSImageValue(rawValue, url, image));
     }
     ~CSSImageValue();
 
     StyleFetchedImage* cachedImage(Document*, const ResourceLoaderOptions&);
     StyleFetchedImage* cachedImage(Document* document) { return cachedImage(document, ResourceFetcher::defaultResourceOptions()); }
     // Returns a StyleFetchedImage if the image is cached already, otherwise a StylePendingImage.
     StyleImage* cachedOrPendingImage();
 
     const String& url() { return m_absoluteURL; }
@@ skipping 10 matching lines @@
     bool equals(const CSSImageValue&) const;
 
     bool knownToBeOpaque(const LayoutObject*) const;
 
     void setInitiator(const AtomicString& name) { m_initiatorName = name; }
 
     DECLARE_TRACE_AFTER_DISPATCH();
     void restoreCachedResourceIfNeeded(Document&);
 
 private:
-    CSSImageValue(const String& rawValue, const KURL&, StyleImage*);
+    CSSImageValue(const AtomicString& rawValue, const KURL&, StyleImage*);
 
-    String m_relativeURL;
-    String m_absoluteURL;
+    AtomicString m_relativeURL;
+    AtomicString m_absoluteURL;
     Referrer m_referrer;
     RefPtrWillBeMember<StyleImage> m_image;
     bool m_accessedImage;
     AtomicString m_initiatorName;
 };
 
 DEFINE_CSS_VALUE_TYPE_CASTS(CSSImageValue, isImageValue());
 
 } // namespace blink
 
 #endif // CSSImageValue_h