Tease apart ServiceWorkerNetworkProvider from other stuff.

content/common/service_worker/service_worker_types.h

Index: content/common/service_worker/service_worker_types.h
diff --git a/content/common/service_worker/service_worker_types.h b/content/common/service_worker/service_worker_types.h
index 10444de002ec58e0ee9ff1136c6aeb1343c6c309..9eccc7b6c5e1eb3095df6e664c9093092af6071f 100644
--- a/content/common/service_worker/service_worker_types.h
+++ b/content/common/service_worker/service_worker_types.h
@@ -22,6 +22,8 @@ namespace content {
 // and embedded worker.
 const static int kInvalidRequestId = -1;
 
+const static int kInvalidServiceWorkerProviderId = -1;
+
 // To dispatch fetch request from browser to child process.
 // TODO(kinuko): This struct will definitely need more fields and
 // we'll probably want to have response struct/class too.