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

content/browser/service_worker/service_worker_registration.h

Index: content/browser/service_worker/service_worker_registration.h
diff --git a/content/browser/service_worker/service_worker_registration.h b/content/browser/service_worker/service_worker_registration.h
index 6f0ebe8eea7d9f21ea6352c462d99956f85cfb85..6f9b0dea86324e017147846e0aa8ebf85bbc2412 100644
--- a/content/browser/service_worker/service_worker_registration.h
+++ b/content/browser/service_worker/service_worker_registration.h
@@ -86,6 +86,10 @@ class CONTENT_EXPORT ServiceWorkerRegistration
     return installing_version_.get();
   }
 
+  bool has_installed_version() const {
+    return active_version() || waiting_version();
+  }
+
   ServiceWorkerVersion* GetNewestVersion() const;
 
   void AddListener(Listener* listener);