Don't create ServiceWorkerProviderHost for sandboxed frames without allow-same-origin flag.

content/child/service_worker/web_service_worker_provider_impl.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/child/service_worker/web_service_worker_provider_impl.h"
 
 #include "content/child/service_worker/service_worker_dispatcher.h"
 #include "content/child/service_worker/service_worker_handle_reference.h"
 #include "content/child/service_worker/service_worker_provider_context.h"
 #include "content/child/service_worker/web_service_worker_impl.h"
 #include "content/child/thread_safe_sender.h"
 #include "third_party/WebKit/public/platform/WebServiceWorkerProviderClient.h"
 #include "third_party/WebKit/public/platform/WebURL.h"
 
 using blink::WebURL;
 
 namespace content {
 
 WebServiceWorkerProviderImpl::WebServiceWorkerProviderImpl(
     ThreadSafeSender* thread_safe_sender,
     ServiceWorkerProviderContext* context)
     : thread_safe_sender_(thread_safe_sender),
       context_(context) {
+  DCHECK(context_);
 }
 
 WebServiceWorkerProviderImpl::~WebServiceWorkerProviderImpl() {
   // Make sure the provider client is removed.
   RemoveProviderClient();
 }
 
 void WebServiceWorkerProviderImpl::setClient(
     blink::WebServiceWorkerProviderClient* client) {
   if (!client) {
@@ skipping 53 matching lines @@
   if (dispatcher)
     dispatcher->RemoveProviderClient(context_->provider_id());
 }
 
 ServiceWorkerDispatcher* WebServiceWorkerProviderImpl::GetDispatcher() {
   return ServiceWorkerDispatcher::GetOrCreateThreadSpecificInstance(
       thread_safe_sender_.get());
 }
 
 }  // namespace content