WebServiceWorkerProxy instances can be unwrapped to ServiceWorkers.

Source/modules/serviceworkers/ServiceWorker.cpp

 /*
  * 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 119 matching lines @@
     case blink::WebServiceWorkerStateActive:
         return active;
     case blink::WebServiceWorkerStateDeactivated:
         return deactivated;
     default:
         ASSERT_NOT_REACHED();
         return nullAtom;
     }
 }
 
+PassRefPtr<ServiceWorker> ServiceWorker::from(ScriptState* scriptState, WebType* worker)
+{
+    blink::WebServiceWorkerProxy* proxy = worker->proxy();
+    ServiceWorker* existingServiceWorker = proxy ? proxy->unwrap() : 0;
+    if (existingServiceWorker) {
+        ASSERT(existingServiceWorker->executionContext() == scriptState->executionContext());
+        return existingServiceWorker;
+    }
+
+    return create(scriptState->executionContext(), adoptPtr(worker));
+}
+
 PassRefPtr<ServiceWorker> ServiceWorker::from(ScriptPromiseResolverWithContext* resolver, WebType* worker)
 {
+    RefPtr<ServiceWorker> serviceWorker = ServiceWorker::from(resolver->scriptState(), worker);
+
     ScriptState::Scope scope(resolver->scriptState());
-    RefPtr<ServiceWorker> serviceWorker = create(resolver->scriptState()->executionContext(), adoptPtr(worker));
     serviceWorker->waitOnPromise(resolver->promise());
+
     return serviceWorker;
 }
 
 void ServiceWorker::onPromiseResolved()
 {
     ASSERT(m_isPromisePending);
     m_isPromisePending = false;
     m_outerWorker->proxyReadyChanged();
 }
 
 void ServiceWorker::waitOnPromise(ScriptPromise promise)
 {
     ASSERT(!m_isPromisePending);
     m_isPromisePending = true;
     m_outerWorker->proxyReadyChanged();
     promise.then(ThenFunction::create(this));
 }
 
 PassRefPtr<ServiceWorker> ServiceWorker::create(ExecutionContext* executionContext, PassOwnPtr<blink::WebServiceWorker> outerWorker)
 {
     RefPtr<ServiceWorker> worker = adoptRef(new ServiceWorker(executionContext, outerWorker));
     worker->suspendIfNeeded();
     return worker.release();
 }
 
 ServiceWorker::ServiceWorker(ExecutionContext* executionContext, PassOwnPtr<blink::WebServiceWorker> worker)
     : AbstractWorker(executionContext)
+    , WebServiceWorkerProxy(this)
     , m_outerWorker(worker)
     , m_isPromisePending(false)
 {
     ScriptWrappable::init(this);
     ASSERT(m_outerWorker);
     m_outerWorker->setProxy(this);
 }
 
 } // namespace WebCore