Declarative resource hints go through mojo IPC to //content

third_party/WebKit/Source/core/loader/NetworkHintsInterface.h

-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef NetworkHintsInterface_h
-#define NetworkHintsInterface_h
-
-#include "platform/network/NetworkHints.h"
-
-namespace blink {
-
-class NetworkHintsInterface {
-public:
-    virtual void dnsPrefetchHost(const String&) const = 0;
-    virtual void preconnectHost(const KURL&, const CrossOriginAttributeValue) const = 0;
-};
-
-class NetworkHintsInterfaceImpl : public NetworkHintsInterface {
-    void dnsPrefetchHost(const String& host) const override
-    {
-        prefetchDNS(host);
-    }
-
-    void preconnectHost(const KURL& host, const CrossOriginAttributeValue crossOrigin) const override
-    {
-        preconnect(host, crossOrigin);
-    }
-};
-
-} // namespace blink
-
-#endif