ServiceWorker: Confirm the liveness of the associated context before handling message

content/browser/service_worker/service_worker_request_handler.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_request_handler.h"
 
 #include "content/browser/service_worker/service_worker_context_core.h"
 #include "content/browser/service_worker/service_worker_context_wrapper.h"
 #include "content/browser/service_worker/service_worker_provider_host.h"
 #include "content/browser/service_worker/service_worker_registration.h"
@@ skipping 52 matching lines @@
     return;
   }
 
   if (!context_wrapper || !context_wrapper->context() ||
       provider_id == kInvalidServiceWorkerProviderId) {
     return;
   }
 
   ServiceWorkerProviderHost* provider_host =
       context_wrapper->context()->GetProviderHost(process_id, provider_id);
-  if (!provider_host)
+  if (!provider_host || !provider_host->IsContextAlive())
     return;
 
   scoped_ptr<ServiceWorkerRequestHandler> handler(
       provider_host->CreateRequestHandler(resource_type,
                                           blob_storage_context->AsWeakPtr()));
   if (!handler)
     return;
 
   request->SetUserData(&kUserDataKey, handler.release());
 }
@@ skipping 18 matching lines @@
     base::WeakPtr<ServiceWorkerProviderHost> provider_host,
     base::WeakPtr<webkit_blob::BlobStorageContext> blob_storage_context,
     ResourceType::Type resource_type)
     : context_(context),
       provider_host_(provider_host),
       blob_storage_context_(blob_storage_context),
       resource_type_(resource_type) {
 }
 
 }  // namespace content