Declarative resource hints go through mojo IPC to //content

third_party/WebKit/Source/platform/network/NetworkHints.h

 /*
  * Copyright (C) 2008 Collin Jackson  <collinj@webkit.org>
  * 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
@@ skipping 12 matching lines @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef NetworkHints_h
 #define NetworkHints_h
 
 #include "platform/CrossOriginAttributeValue.h"
 #include "platform/PlatformExport.h"
 #include "platform/weborigin/KURL.h"
+#include "public/platform/resource_hints.mojom-blink.h"
 #include "wtf/Forward.h"
 
 namespace blink {
 
-PLATFORM_EXPORT void prefetchDNS(const String& hostname);
+// This is used for speculative prefetches that are only enabled for HTTP sites.
+// This includes <a> tag scanning and mouse hover predictions.
+PLATFORM_EXPORT void speculativePrefetchDNS(const String& hostname);
+
+PLATFORM_EXPORT void prefetchDNS(const KURL&);
 PLATFORM_EXPORT void preconnect(const KURL&, const CrossOriginAttributeValue);
 
+class ResourceHintsDispatcher {

[yzshen1, 2016/06/08 17:40:53]

It seems this class can be hidden in an anonymous namespace in NetworkHints.cpp?

[Charlie Harrison, 2016/06/10 14:20:00]

Done.

+public:
+    static ResourceHintsDispatcher& instance();
+    void preconnect(const KURL&, CrossOriginAttributeValue, int numConnections);
+    void preresolve(const KURL&);
+
+private:
+    ResourceHintsDispatcher();
+    mojom::blink::ResourceHintsDispatcherHostPtr m_host;
+};
+
 } // namespace blink
 
 #endif