Introduce ServiceWorkerHandle for tracking WebServiceWorkerImpl reference

content/browser/service_worker/service_worker_unregister_job.cc

 // 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.
 
 #include "content/browser/service_worker/service_worker_unregister_job.h"
 
 #include "content/browser/service_worker/service_worker_context_core.h"
 #include "content/browser/service_worker/service_worker_job_coordinator.h"
 #include "content/browser/service_worker/service_worker_registration.h"
 #include "content/browser/service_worker/service_worker_storage.h"
@@ skipping 30 matching lines @@
 }
 
 RegistrationJobType ServiceWorkerUnregisterJob::GetType() {
   return ServiceWorkerRegisterJobBase::UNREGISTER;
 }
 
 void ServiceWorkerUnregisterJob::DeleteExistingRegistration(
     ServiceWorkerStatusCode status,
     const scoped_refptr<ServiceWorkerRegistration>& registration) {
   if (status == SERVICE_WORKER_OK) {
-    registration->Shutdown();
     context_->storage()->DeleteRegistration(
         pattern_,
         base::Bind(&ServiceWorkerUnregisterJob::Complete,
                    weak_factory_.GetWeakPtr()));
     return;
   }
 
   if (status == SERVICE_WORKER_ERROR_NOT_FOUND) {
     // The previous registration does not exist, which is ok.
     Complete(SERVICE_WORKER_OK);
     return;
   }
 
   Complete(status);
 }
 
 void ServiceWorkerUnregisterJob::Complete(ServiceWorkerStatusCode status) {
   for (std::vector<UnregistrationCallback>::iterator it = callbacks_.begin();
        it != callbacks_.end();
        ++it) {
     it->Run(status);
   }
   context_->job_coordinator()->FinishJob(pattern_, this);
 }
 
 }  // namespace content