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

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

Index: third_party/WebKit/Source/core/loader/DocumentLoader.cpp
diff --git a/third_party/WebKit/Source/core/loader/DocumentLoader.cpp b/third_party/WebKit/Source/core/loader/DocumentLoader.cpp
index f17bb791a94af1a3547f8417069ebef192336a70..725c4f3f1192cdf1ebef89e6a40827fd6c4f9222 100644
--- a/third_party/WebKit/Source/core/loader/DocumentLoader.cpp
+++ b/third_party/WebKit/Source/core/loader/DocumentLoader.cpp
@@ -56,6 +56,7 @@
 #include "core/loader/FrameLoader.h"
 #include "core/loader/FrameLoaderClient.h"
 #include "core/loader/LinkLoader.h"
+#include "core/loader/LinkPreloadResourceClients.h"
 #include "core/loader/ProgressTracker.h"
 #include "core/loader/appcache/ApplicationCacheHost.h"
 #include "core/page/FrameTree.h"
@@ -160,18 +161,22 @@ const KURL& DocumentLoader::url() const
     return m_request.url();
 }
 
-void DocumentLoader::startPreload(Resource::Type type, FetchRequest& request)
+void DocumentLoader::startPreload(Resource::Type type, FetchRequest& request, LinkLoader* linkLoader)
 {
     ResourcePtr<Resource> resource;
+    OwnPtr<LinkPreloadResourceClient> resourceClient = nullptr;
     switch (type) {
     case Resource::Image:
         resource = ImageResource::fetch(request, fetcher());
+        resourceClient = LinkPreloadImageResourceClient::create(linkLoader, resource.get());
         break;
     case Resource::Script:
         resource = ScriptResource::fetch(request, fetcher());
+        resourceClient = LinkPreloadScriptResourceClient::create(linkLoader, resource.get());
         break;
     case Resource::CSSStyleSheet:
         resource = CSSStyleSheetResource::fetch(request, fetcher());
+        resourceClient = LinkPreloadStyleResourceClient::create(linkLoader, resource.get());
         break;
     case Resource::Font:
         resource = FontResource::fetch(request, fetcher());
@@ -192,8 +197,12 @@ void DocumentLoader::startPreload(Resource::Type type, FetchRequest& request)
         ASSERT_NOT_REACHED();
     }
 
-    if (resource)
-        fetcher()->preloadStarted(resource.get());
+    if (!resource)
+        return;
+
+    if (linkLoader)
+        linkLoader->setPreloadResourceClient(resourceClient.release());
+    fetcher()->preloadStarted(resource.get());
 }
 
 void DocumentLoader::didChangePerformanceTiming()