Don't speculatively start ServiceWorker if it doesn't have FetchEvent handler

content/browser/service_worker/service_worker_context_wrapper.cc

 // 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.
 
 #include "content/browser/service_worker/service_worker_context_wrapper.h"
 
 #include <map>
 #include <set>
 #include <string>
 #include <utility>
@@ skipping 323 matching lines @@
     const ResultCallback& callback,
     ServiceWorkerStatusCode status,
     scoped_refptr<ServiceWorkerRegistration> registration) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   if (status != SERVICE_WORKER_OK || !registration->active_version()) {
     BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
                             base::Bind(callback, false));
     return;
   }
 
+  if (registration->active_version()->fetch_handler_existence() ==
+      ServiceWorkerVersion::FetchHandlerExistence::DOES_NOT_EXIST) {
+    BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
+                            base::Bind(callback, false));
+    return;
+  }
+
   // Add the process reference of |render_process_id| not to launch a new
   // renderer process for the service worker.
   context_core_->process_manager()->AddProcessReferenceToPattern(
       registration->pattern(), render_process_id);
 
   registration->active_version()->StartWorker(
       GetNavigationHintEventType(type),
       base::Bind(
           &ServiceWorkerContextWrapper::DidStartServiceWorkerForNavigationHint,
           this, registration->pattern(), render_process_id, callback));
@@ skipping 484 matching lines @@
   observer_list_->Notify(FROM_HERE,
                          &ServiceWorkerContextObserver::OnStorageWiped);
 }
 
 ServiceWorkerContextCore* ServiceWorkerContextWrapper::context() {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   return context_core_.get();
 }
 
 }  // namespace content