Add initial link preload support

Source/core/loader/LinkLoader.h

 /*
  * Copyright (C) 2011 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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 45 matching lines @@
     // from ResourceClient
     virtual void notifyFinished(Resource*) override;
 
     // from PrerenderClient
     virtual void didStartPrerender() override;
     virtual void didStopPrerender() override;
     virtual void didSendLoadForPrerender() override;
     virtual void didSendDOMContentLoadedForPrerender() override;
 
     void released();
-    bool loadLink(const LinkRelAttribute&, const AtomicString& crossOriginMode, const String& type, const KURL&, Document&);
+    bool loadLink(const LinkRelAttribute&, const AtomicString& crossOriginMode, const String& type, const String& as, const KURL&, Document&);
     static bool loadLinkFromHeader(const String& headerValue, Document*);
 
     DECLARE_TRACE();
 
 private:
     void linkLoadTimerFired(Timer<LinkLoader>*);
     void linkLoadingErrorTimerFired(Timer<LinkLoader>*);
+    void preloadIfNeeded(const LinkRelAttribute&, const KURL& href, Document&, const String& as);
 
     LinkLoaderClient* m_client;
 
     Timer<LinkLoader> m_linkLoadTimer;
     Timer<LinkLoader> m_linkLoadingErrorTimer;
 
     OwnPtrWillBeMember<PrerenderHandle> m_prerender;
 };
 
 }
 
 #endif