Add <link rel=preload> onload support for scripts and styles

third_party/WebKit/Source/core/loader/DocumentLoader.h

 /*
  * Copyright (C) 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 128 matching lines @@
         {
         }
 
         bool wasScrolledByUser;
         bool didRestoreFromHistory;
     };
     InitialScrollState& initialScrollState() { return m_initialScrollState; }
 
     bool loadingMultipartContent() const;
 
-    void startPreload(Resource::Type, FetchRequest&);
+    ResourcePtr<Resource> startPreload(Resource::Type, FetchRequest&);
 
     DECLARE_VIRTUAL_TRACE();
 
 protected:
     DocumentLoader(LocalFrame*, const ResourceRequest&, const SubstituteData&);
 
     Vector<KURL> m_redirectChain;
 
 private:
     static PassRefPtrWillBeRawPtr<DocumentWriter> createWriterFor(const Document* ownerDocument, const DocumentInit&, const AtomicString& mimeType, const AtomicString& encoding, bool dispatch, ParserSynchronizationPolicy);
@@ skipping 82 matching lines @@
     // Used to protect against reentrancy into dataReceived().
     bool m_inDataReceived;
     RefPtr<SharedBuffer> m_dataBuffer;
 };
 
 DECLARE_WEAK_IDENTIFIER_MAP(DocumentLoader);
 
 } // namespace blink
 
 #endif // DocumentLoader_h