Declarative resource hints go through mojo IPC to //content

third_party/WebKit/Source/platform/PlatformMojoInterface.cpp

+// Copyright 2016 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.
+
+#include "platform/PlatformMojoInterface.h"
+
+#include "public/platform/Platform.h"
+#include "public/platform/ServiceRegistry.h"
+
+namespace blink {
+
+PlatformMojoInterface::PlatformMojoInterface()
+{
+}
+
+const mojom::blink::ResourceHintsHandlerPtr& PlatformMojoInterface::resourceHintsHandlerHost()
+{
+    // Lazily bind to the service.
+    if (!m_resourceHintsHandlerHost.is_bound()) {
+        Platform::current()->serviceRegistry()->connectToRemoteService(mojo::GetProxy(&m_resourceHintsHandlerHost));
+    }
+    return m_resourceHintsHandlerHost;
+}
+
+} // namespace blink