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

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

 /*
  * Copyright (C) 2006, 2007, 2008 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 142 matching lines @@
 const ResourceRequest& DocumentLoader::request() const
 {
     return m_request;
 }
 
 const KURL& DocumentLoader::url() const
 {
     return m_request.url();
 }
 
-void DocumentLoader::startPreload(Resource::Type type, FetchRequest& request)
+ResourcePtr<Resource> DocumentLoader::startPreload(Resource::Type type, FetchRequest& request)
 {
     ResourcePtr<Resource> resource;
     switch (type) {
     case Resource::Image:
         resource = ImageResource::fetch(request, fetcher());
         break;
     case Resource::Script:
         resource = ScriptResource::fetch(request, fetcher());
         break;
     case Resource::CSSStyleSheet:
@@ skipping 15 matching lines @@
         break;
     case Resource::LinkSubresource:
         resource = RawResource::fetch(request, fetcher());
         break;
     default:
         ASSERT_NOT_REACHED();
     }
 
     if (resource)
         fetcher()->preloadStarted(resource.get());
+    return resource;
 }
 
 void DocumentLoader::didChangePerformanceTiming()
 {
     if (frame() && frame()->isMainFrame() && m_state >= Committed) {
         frameLoader()->client()->didChangePerformanceTiming();
     }
 }
 
 void DocumentLoader::updateForSameDocumentNavigation(const KURL& newURL, SameDocumentNavigationSource sameDocumentNavigationSource)
@@ skipping 636 matching lines @@
 {
     m_writer = createWriterFor(ownerDocument, init, mimeType(), m_writer ? m_writer->encoding() : emptyAtom, true, ForceSynchronousParsing);
     if (!source.isNull())
         m_writer->appendReplacingData(source);
     endWriting(m_writer.get());
 }
 
 DEFINE_WEAK_IDENTIFIER_MAP(DocumentLoader);
 
 } // namespace blink