service worker: use 200 OK for update requests even in the no update case

content/browser/service_worker/service_worker_registration.h

 // Copyright 2013 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 CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_REGISTRATION_H_
 #define CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_REGISTRATION_H_
 
 #include <stdint.h>
 
 #include <string>
@@ skipping 68 matching lines @@
   }
 
   ServiceWorkerVersion* waiting_version() const {
     return waiting_version_.get();
   }
 
   ServiceWorkerVersion* installing_version() const {
     return installing_version_.get();
   }
 
+  bool has_installed_version() const {
+    return active_version() || waiting_version();
+  }
+
   ServiceWorkerVersion* GetNewestVersion() const;
 
   void AddListener(Listener* listener);
   void RemoveListener(Listener* listener);
   void NotifyRegistrationFailed();
   void NotifyUpdateFound();
   void NotifyVersionAttributesChanged(ChangedVersionAttributesMask mask);
 
   ServiceWorkerRegistrationInfo GetInfo();
 
@@ skipping 90 matching lines @@
   base::ObserverList<Listener> listeners_;
   std::vector<base::Closure> registration_finished_callbacks_;
   base::WeakPtr<ServiceWorkerContextCore> context_;
 
   DISALLOW_COPY_AND_ASSIGN(ServiceWorkerRegistration);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_REGISTRATION_H_