Reland: Add test for system tray network menu icon for extension-controlled networks

ash/common/system/networking_config_delegate.h

Index: ash/common/system/networking_config_delegate.h
diff --git a/ash/common/system/networking_config_delegate.h b/ash/common/system/networking_config_delegate.h
index d136649bcdd36dd85b1dc969dfedcc892dcd6cde..e7c607dddd042aa9664a020164f476b97837492a 100644
--- a/ash/common/system/networking_config_delegate.h
+++ b/ash/common/system/networking_config_delegate.h
@@ -17,6 +17,9 @@ namespace ash {
 // to access the |NetworkingConfigService| in order to determine whether the
 // configuration of a network identified by its |service_path| is controlled by
 // an extension.
+// TODO(crbug.com/651157): Eliminate this delegate. Information about extension
+// controlled networks should be provided by a mojo service that caches data at
+// the NetworkState level.
 class NetworkingConfigDelegate {
  public:
   // A struct that provides information about the extension controlling the