Remove resource type-specific fetching logic from ResourceFetcher

Source/core/loader/DocumentLoader.cpp

Index: Source/core/loader/DocumentLoader.cpp
diff --git a/Source/core/loader/DocumentLoader.cpp b/Source/core/loader/DocumentLoader.cpp
index 34953db4e9194847766ef6bcaa3a0dc7ec29d834..ce0213cc2f7d55ced5e0293d4d37064e8cc5a621 100644
--- a/Source/core/loader/DocumentLoader.cpp
+++ b/Source/core/loader/DocumentLoader.cpp
@@ -34,10 +34,14 @@
 #include "core/dom/DocumentParser.h"
 #include "core/dom/WeakIdentifierMap.h"
 #include "core/events/Event.h"
+#include "core/fetch/CSSStyleSheetResource.h"
 #include "core/fetch/FetchInitiatorTypeNames.h"
+#include "core/fetch/FetchRequest.h"
+#include "core/fetch/ImageResource.h"
 #include "core/fetch/MemoryCache.h"
 #include "core/fetch/ResourceFetcher.h"
 #include "core/fetch/ResourceLoader.h"
+#include "core/fetch/ScriptResource.h"
 #include "core/frame/FrameHost.h"
 #include "core/frame/LocalDOMWindow.h"
 #include "core/frame/LocalFrame.h"
@@ -139,6 +143,21 @@ const KURL& DocumentLoader::url() const
     return m_request.url();
 }
 
+void DocumentLoader::startPreload(Resource::Type type, FetchRequest& request)
+{
+    ASSERT(type == Resource::Script || type == Resource::CSSStyleSheet || type == Resource::Image);
+    ResourcePtr<Resource> resource;
+    if (type == Resource::Image)
+        resource = ImageResource::fetch(request, fetcher());
+    else if (type == Resource::Script)
+        resource = ScriptResource::fetch(request, fetcher());
+    else
+        resource = CSSStyleSheetResource::fetch(request, fetcher());
+
+    if (resource)
+        fetcher()->preloadStarted(resource.get());
+}
+
 void DocumentLoader::updateForSameDocumentNavigation(const KURL& newURL, SameDocumentNavigationSource sameDocumentNavigationSource)
 {
     KURL oldURL = m_request.url();
@@ -690,7 +709,7 @@ void DocumentLoader::startLoadingMainResource()
     DEFINE_STATIC_LOCAL(ResourceLoaderOptions, mainResourceLoadOptions,
         (DoNotBufferData, AllowStoredCredentials, ClientRequestedCredentials, CheckContentSecurityPolicy, DocumentContext));
     FetchRequest cachedResourceRequest(request, FetchInitiatorTypeNames::document, mainResourceLoadOptions);
-    m_mainResource = m_fetcher->fetchMainResource(cachedResourceRequest, m_substituteData);
+    m_mainResource = RawResource::fetchMainResource(cachedResourceRequest, fetcher(), m_substituteData);
     if (!m_mainResource) {
         m_request = ResourceRequest();
         // If the load was aborted by clearing m_request, it's possible the ApplicationCacheHost