[WIP2] off-main-thread loading

content/renderer/service_worker/service_worker_fetch_context_impl.cc

Index: content/renderer/service_worker/service_worker_fetch_context_impl.cc
diff --git a/content/renderer/service_worker/service_worker_fetch_context_impl.cc b/content/renderer/service_worker/service_worker_fetch_context_impl.cc
index 3806edb4dbf6545215ef3da25274286b206829eb..ebeb2fb663980c3711e73db8b88b8ea310230aee 100644
--- a/content/renderer/service_worker/service_worker_fetch_context_impl.cc
+++ b/content/renderer/service_worker/service_worker_fetch_context_impl.cc
@@ -40,10 +40,17 @@ void ServiceWorkerFetchContextImpl::WillSendRequest(
   extra_data->set_originated_from_service_worker(true);
   extra_data->set_initiated_in_secure_context(true);
   request.SetExtraData(extra_data);
+
+  if (data_saver_enabled_)
+    request.SetHTTPHeaderField("Save-Data", "on");
 }
 
 bool ServiceWorkerFetchContextImpl::IsControlledByServiceWorker() const {
   return false;
 }
 
+void ServiceWorkerFetchContextImpl::SetDataSaverEnabled(bool flag) {
+  data_saver_enabled_ = flag;
+}
+
 }  // namespace content