Declarative resource hints go through mojo IPC to //content

third_party/WebKit/Source/platform/PlatformMojoServices.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/PlatformMojoServices.h"
+
+#include "public/platform/Platform.h"
+#include "public/platform/ServiceRegistry.h"
+
+namespace blink {
+
+PlatformMojoServices::PlatformMojoServices()
+{
+}
+
+const mojom::blink::ResourceHintsHandlerPtr& PlatformMojoServices::resourceHintsHandler()
+{

[kinuko, 2016/06/23 15:38:07]

Platform methods are exposed to any threads so potentially this could be called
on any threads.  Currently we assume this is only called on main thread, is that
right?  Could we add isMainThread assertion here?

+    // Lazily bind to the service.
+    if (!m_resourceHintsHandler.is_bound()) {
+        Platform::current()->serviceRegistry()->connectToRemoteService(mojo::GetProxy(&m_resourceHintsHandler));
+    }
+    return m_resourceHintsHandler;
+}
+
+} // namespace blink