Preload scan external css for @import

third_party/WebKit/Source/core/html/parser/HTMLResourcePreloader.cpp

Index: third_party/WebKit/Source/core/html/parser/HTMLResourcePreloader.cpp
diff --git a/third_party/WebKit/Source/core/html/parser/HTMLResourcePreloader.cpp b/third_party/WebKit/Source/core/html/parser/HTMLResourcePreloader.cpp
index e29b24e804a733d7b7c9ad0988b400cea1eb9193..88bf5409336fef8be9b651a9d47d7c5d63322a54 100644
--- a/third_party/WebKit/Source/core/html/parser/HTMLResourcePreloader.cpp
+++ b/third_party/WebKit/Source/core/html/parser/HTMLResourcePreloader.cpp
@@ -26,6 +26,7 @@
 #include "core/html/parser/HTMLResourcePreloader.h"
 
 #include "core/dom/Document.h"
+#include "core/fetch/CSSStyleSheetResource.h"
 #include "core/fetch/FetchInitiatorInfo.h"
 #include "core/fetch/ResourceFetcher.h"
 #include "core/loader/DocumentLoader.h"
@@ -48,6 +49,13 @@ DEFINE_TRACE(HTMLResourcePreloader)
     visitor->trace(m_document);
 }
 
+int HTMLResourcePreloader::countPreloads()
+{
+    if (m_document->loader())
+        return m_document->loader()->fetcher()->countPreloads();
+    return 0;
+}
+
 static void preconnectHost(PreloadRequest* request, const NetworkHintsInterface& networkHintsInterface)
 {
     ASSERT(request);
@@ -75,7 +83,12 @@ void HTMLResourcePreloader::preload(PassOwnPtr<PreloadRequest> preload, const Ne
     if (preload->resourceType() == Resource::Script || preload->resourceType() == Resource::CSSStyleSheet || preload->resourceType() == Resource::ImportResource)
         request.setCharset(preload->charset().isEmpty() ? m_document->characterSet().getString() : preload->charset());
     request.setForPreload(true);
-    m_document->loader()->startPreload(preload->resourceType(), request);
+    Resource* resource = m_document->loader()->startPreload(preload->resourceType(), request);
+    if (resource && preload->resourceType() == Resource::CSSStyleSheet && RuntimeEnabledFeatures::cssPreloadImportEnabled()) {
+        OwnPtr<CSSPreloaderResourceClient> client = adoptPtr(new CSSPreloaderResourceClient(resource, this));
+        resource->addClient(client.get());
+        m_cssPreloaders.add(client.release());
+    }
 }
 
 } // namespace blink