Introduce SystemNetworkContextManager.

content/public/browser/network_service_instance.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/public/browser/network_service_instance.h"
+
+#include "base/feature_list.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/common/content_features.h"
+#include "content/public/common/network_service.mojom.h"
+#include "content/public/common/service_manager_connection.h"
+#include "content/public/common/service_names.mojom.h"
+#include "services/service_manager/public/cpp/connector.h"
+
+namespace content {
+
+mojom::NetworkService* GetNetworkService() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  DCHECK(base::FeatureList::IsEnabled(features::kNetworkService));
+
+  static mojom::NetworkServicePtr* g_network_service =
+      new mojom::NetworkServicePtr;
+  if (!g_network_service->is_bound()) {
+    ServiceManagerConnection::GetForProcess()->GetConnector()->BindInterface(
+        mojom::kNetworkServiceName, g_network_service);
+  }
+  return g_network_service->get();
+}
+
+}  // namespace content