WebServiceWorkerProxy instances can be unwrapped to ServiceWorkers.

public/platform/WebServiceWorkerProxy.h

 // Copyright 2014 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 WebServiceWorkerProxy_h
 #define WebServiceWorkerProxy_h
 
+#include "WebCommon.h"
+
+namespace WebCore { class ServiceWorker; }
+
 namespace blink {
 
 // A proxy interface, passed via WebServiceWorker.setProxy() from blink to
 // the embedder, to talk to the ServiceWorker object from embedder.
 class WebServiceWorkerProxy {
 public:
+    WebServiceWorkerProxy() : m_private(0) { }
+    virtual ~WebServiceWorkerProxy() { }
+
     // Returns true if the proxy is ready to be notified of service worker state
     // changes. It may not be if it's waiting for the registration promise to
     // resolve, while the browser side has registered and is proceeding to
     // install and activate the worker.
     virtual bool isReady() = 0;
 
     // Notifies the proxy that the service worker state changed. The new state
     // should be accessible via WebServiceWorker.state().
     virtual void dispatchStateChangeEvent() = 0;
+
+#if INSIDE_BLINK
+    BLINK_PLATFORM_EXPORT WebServiceWorkerProxy(WebCore::ServiceWorker*);
+    BLINK_PLATFORM_EXPORT WebCore::ServiceWorker* unwrap() const;
+#endif
+
+protected:
+    WebCore::ServiceWorker* m_private;
 };
 
 } // namespace blink
 
 #endif // WebServiceWorkerProxy_h