[WIP2] off-main-thread loading

content/renderer/service_worker/service_worker_fetch_context_impl.cc

 // Copyright 2017 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/renderer/service_worker/service_worker_fetch_context_impl.h"
 
 #include "content/child/request_extra_data.h"
 #include "content/child/resource_dispatcher.h"
 #include "content/child/web_url_loader_impl.h"
 
@@ skipping 22 matching lines @@
                                                      url_loader_factory_.get());
 }
 
 void ServiceWorkerFetchContextImpl::WillSendRequest(
     blink::WebURLRequest& request) {
   RequestExtraData* extra_data = new RequestExtraData();
   extra_data->set_service_worker_provider_id(service_worker_provider_id_);
   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