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

content/browser/service_worker/service_worker_context_wrapper.cc

Index: content/browser/service_worker/service_worker_context_wrapper.cc
diff --git a/content/browser/service_worker/service_worker_context_wrapper.cc b/content/browser/service_worker/service_worker_context_wrapper.cc
index 460f6df36e402ba3d498695ff545930cfb3b9eb3..a9401d60381ddda1d9dec326350511782d7ace95 100644
--- a/content/browser/service_worker/service_worker_context_wrapper.cc
+++ b/content/browser/service_worker/service_worker_context_wrapper.cc
@@ -9,6 +9,7 @@
 #include "content/browser/service_worker/service_worker_context_core.h"
 #include "content/browser/service_worker/service_worker_context_observer.h"
 #include "content/browser/service_worker/service_worker_process_manager.h"
+#include "content/browser/service_worker/service_worker_provider_host_registry.h"
 #include "content/public/browser/browser_thread.h"
 #include "webkit/browser/quota/quota_manager_proxy.h"
 
@@ -156,10 +157,14 @@ void ServiceWorkerContextWrapper::InitInternal(
                                                    quota_manager_proxy,
                                                    observer_list_,
                                                    this));
+  provider_registry_.reset(new ServiceWorkerProviderHostRegistry);
 }
 
 void ServiceWorkerContextWrapper::ShutdownOnIO() {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  // TODO(nhiroki): Don't have to reset the registry on DeleteAndStartOver().
+  // (http://crbug.com/371675)
+  provider_registry_.reset();
   context_core_.reset();
 }