Prefetch @import files from CSS files.

Source/core/fetch/CSSStyleSheetResource.h

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller <mueller@kde.org>
     Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
     Copyright (C) 2004, 2005, 2006, 2007, 2008 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.
@@ skipping 10 matching lines @@
 
     This class provides all functionality needed for loading images, style sheets and html
     pages from the web. It has a memory cache for these objects.
 */
 
 #ifndef CSSStyleSheetResource_h
 #define CSSStyleSheetResource_h
 
 #include "core/fetch/ResourcePtr.h"
 #include "core/fetch/StyleSheetResource.h"
+#include "core/html/parser/CSSPreloadScanner.h"
 #include "heap/Handle.h"
 
 namespace WebCore {
 
 class CSSParserContext;
 class ResourceClient;
 class StyleSheetContents;
 class TextResourceDecoder;
 
 class CSSStyleSheetResource FINAL : public StyleSheetResource {
 public:
-    CSSStyleSheetResource(const ResourceRequest&, const String& charset);
+    CSSStyleSheetResource(const ResourceRequest&, const String& charset, Document*);

[abarth-chromium, 2014/02/26 19:13:36]

You can't have a dependency from a subclass of Resource to Document.  Resources
are shared by multiple documents.

     virtual ~CSSStyleSheetResource();
 
     const String sheetText(bool enforceMIMEType = true, bool* hasValidMIMEType = 0) const;
 
     virtual void didAddClient(ResourceClient*) OVERRIDE;
     virtual void setEncoding(const String&) OVERRIDE;
     virtual String encoding() const OVERRIDE;
 
     PassRefPtrWillBeRawPtr<StyleSheetContents> restoreParsedStyleSheet(const CSSParserContext&);
     void saveParsedStyleSheet(PassRefPtrWillBeRawPtr<StyleSheetContents>);
 
 protected:
     virtual bool isSafeToUnlock() const OVERRIDE;
     virtual void destroyDecodedDataIfPossible() OVERRIDE;
 
 private:
     bool canUseSheet(bool enforceMIMEType, bool* hasValidMIMEType) const;
     virtual void checkNotify() OVERRIDE;
+    virtual void appendData(const char*, int) OVERRIDE;
 
     OwnPtr<TextResourceDecoder> m_decoder;
     String m_decodedSheetText;
 
+    OwnPtr<CSSPreloadScanner> m_preloadScanner;
+    OwnPtr<HTMLResourcePreloader> m_preloader;
+    bool m_prescan;

[abarth-chromium, 2014/02/26 19:13:36]

What do m_prescan mean?  Does this mean m_isPreloadScanning?  Can we use the
nullity of m_preloadScanner to check for that instead?

+
     RefPtrWillBePersistent<StyleSheetContents> m_parsedStyleSheetCache;
 };
 
 DEFINE_RESOURCE_TYPE_CASTS(CSSStyleSheet);
 
 }
 
 #endif