Introduce ServiceWorkerHandle for tracking WebServiceWorkerImpl reference

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 5d262e572747ce9a5934a759ff307bea37147701..6a2b6932c5033bbeb9f27dfed01992531a8cb084 100644
--- a/content/browser/service_worker/service_worker_registration.h
+++ b/content/browser/service_worker/service_worker_registration.h
@@ -40,9 +40,6 @@ class CONTENT_EXPORT ServiceWorkerRegistration
                             int64 registration_id,
                             base::WeakPtr<ServiceWorkerContextCore> context);
 
-  void Shutdown();
-  bool is_shutdown() const { return is_shutdown_; }
-
   int64 id() const { return registration_id_; }
   const GURL& script_url() const { return script_url_; }
   const GURL& pattern() const { return pattern_; }