Add Windows and Mac network list implementation

chrome/browser/media/router/discovery/discovery_network_list_wifi_mac.mm

Index: chrome/browser/media/router/discovery/discovery_network_list_wifi_mac.mm
diff --git a/chrome/browser/media/router/discovery/discovery_network_list_wifi_mac.mm b/chrome/browser/media/router/discovery/discovery_network_list_wifi_mac.mm
new file mode 100644
index 0000000000000000000000000000000000000000..c782117cb60a2d3e664a50ed1978c88fbf7ff918
--- /dev/null
+++ b/chrome/browser/media/router/discovery/discovery_network_list_wifi_mac.mm
@@ -0,0 +1,30 @@
+// 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.
+
+#include "chrome/browser/media/router/discovery/discovery_network_list_wifi.h"
+
+#include <CoreWLAN/CoreWLAN.h>
+#include <string.h>
+
+#include <utility>
+
+#include "base/logging.h"
+#include "base/mac/scoped_nsobject.h"
+#include "base/strings/sys_string_conversions.h"
+
+bool MaybeGetWifiSSID(const std::string& if_name, std::string* ssid_out) {
+  DCHECK(ssid_out);
+
+  NSString* ns_ifname = base::SysUTF8ToNSString(if_name.data());
+  CWInterface* interface = [CWInterface interfaceWithName:ns_ifname];
+  if (interface == nil) {
+    return false;
+  }
+  std::string ssid(base::SysNSStringToUTF8([interface ssid]));
+  if (ssid.size() == 0) {
+    return false;
+  }
+  ssid_out->assign(std::move(ssid));
+  return true;
+}