Preload scan external CSS for @import

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

 /*
  * Copyright (C) 2013 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.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #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/frame/Settings.h"
 #include "core/loader/DocumentLoader.h"
 #include "platform/Histogram.h"
 #include "public/platform/Platform.h"
 #include <memory>
 
 namespace blink {
 
 inline HTMLResourcePreloader::HTMLResourcePreloader(Document& document)
     : m_document(document)
 {
 }
 
 HTMLResourcePreloader* HTMLResourcePreloader::create(Document& document)
 {
     return new HTMLResourcePreloader(document);
 }
 
 DEFINE_TRACE(HTMLResourcePreloader)
 {
     visitor->trace(m_document);
+    visitor->trace(m_cssPreloaders);
+}
+
+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);
     ASSERT(request->isPreconnect());
     KURL host(request->baseURL(), request->resourceURL());
     if (!host.isValid() || !host.protocolIsInHTTPFamily())
         return;
     networkHintsInterface.preconnectHost(host, request->crossOrigin());
@@ skipping 12 matching lines @@
     // TODO(dgozman): This check should go to HTMLPreloadScanner, but this requires
     // making Document::completeURLWithOverride logic to be statically accessible.
     if (request.url().protocolIsData())
         return;
     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, preload->discoveryTime());
     int duration = static_cast<int>(1000 * (monotonicallyIncreasingTime() - preload->discoveryTime()));
     DEFINE_STATIC_LOCAL(CustomCountHistogram, preloadDelayHistogram, ("WebCore.PreloadDelayMs", 0, 2000, 20));
     preloadDelayHistogram.count(duration);
-    m_document->loader()->startPreload(preload->resourceType(), request);
+
+    Resource* resource = m_document->loader()->startPreload(preload->resourceType(), request);
+    // Note that if the cssExternalScanner{Preload,NoPreload} settings flags are
+    // not set, this resource client does nothing.
+    if (resource && preload->resourceType() == Resource::CSSStyleSheet) {
+        Settings* settings = m_document->settings();
+        if (!settings)
+            return;
+        if (!settings->cssExternalScannerNoPreload() && !settings->cssExternalScannerPreload()) {
+            return;
+        }
+        m_cssPreloaders.add(new CSSPreloaderResourceClient(resource, this));
+    }
 }
 
 } // namespace blink