(Not for review) Dummy C++ side Custom Controls implementation

chrome/browser/media/router/media_route_status_observer.h

+// 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.
+
+#ifndef CHROME_BROWSER_MEDIA_ROUTER_MEDIA_ROUTE_STATUS_OBSERVER_H_
+#define CHROME_BROWSER_MEDIA_ROUTER_MEDIA_ROUTE_STATUS_OBSERVER_H_
+
+struct MediaStatus;
+
+namespace media_router {
+
+class MediaRouteStatusObserver {
+ public:
+  MediaRouteStatusObserver() {}
+  virtual ~MediaRouteStatusObserver() {}
+
+  virtual void OnMediaRouteStatusUpdated(const MediaStatus& status) = 0;
+};
+
+}  // namespace media_router
+
+#endif  // CHROME_BROWSER_MEDIA_ROUTER_MEDIA_ROUTE_STATUS_OBSERVER_H_