ServiceWorker: Initialize EmbeddedWorkerInstanceClientImpl::wrapper_

content/renderer/service_worker/embedded_worker_instance_client_impl.h

Index: content/renderer/service_worker/embedded_worker_instance_client_impl.h
diff --git a/content/renderer/service_worker/embedded_worker_instance_client_impl.h b/content/renderer/service_worker/embedded_worker_instance_client_impl.h
index c41aade28d13a84340db7c16762332b583ee90e7..9cae1fe11877d9d99ffc40cbe18928e383365305 100644
--- a/content/renderer/service_worker/embedded_worker_instance_client_impl.h
+++ b/content/renderer/service_worker/embedded_worker_instance_client_impl.h
@@ -63,7 +63,9 @@ class EmbeddedWorkerInstanceClientImpl
   service_manager::mojom::InterfaceProviderRequest renderer_request_;
 
   base::Optional<int> embedded_worker_id_;
-  // Owned by EmbeddedWorkerDispatcher
+
+  // Owned by EmbeddedWorkerDispatcher. This can be nullptr while a worker is
+  // not running.
   EmbeddedWorkerDispatcher::WorkerWrapper* wrapper_;
 
   StopWorkerCallback stop_callback_;