Add DiscoveryNetworkMonitor implementation

chrome/browser/media/router/discovery/discovery_network_list.h

Index: chrome/browser/media/router/discovery/discovery_network_list.h
diff --git a/chrome/browser/media/router/discovery/discovery_network_list.h b/chrome/browser/media/router/discovery/discovery_network_list.h
new file mode 100644
index 0000000000000000000000000000000000000000..c5101a306a1d787c9183d9a95a3b7ec712dd31d7
--- /dev/null
+++ b/chrome/browser/media/router/discovery/discovery_network_list.h
@@ -0,0 +1,17 @@
+// Copyright (c) 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.
+
+#ifndef CHROME_BROWSER_MEDIA_ROUTER_DISCOVERY_DISCOVERY_NETWORK_LIST_H_
+#define CHROME_BROWSER_MEDIA_ROUTER_DISCOVERY_DISCOVERY_NETWORK_LIST_H_
+
+#include <vector>
+
+#include "chrome/browser/media/router/discovery/discovery_network_info.h"
+
+// Returns a list of information about each network to which the host is
+// connected, stable-sorted by network ID (stable relative to the order they are
+// returned by the OS during enumeration).
+std::vector<DiscoveryNetworkInfo> GetDiscoveryNetworkInfoList();
+
+#endif  // CHROME_BROWSER_MEDIA_ROUTER_DISCOVERY_DISCOVERY_NETWORK_LIST_H_