Add media router common classes and unittests.

chrome/browser/media/router/media_route_id.h

Index: chrome/browser/media/router/media_route_id.h
diff --git a/chrome/browser/media/router/media_route_id.h b/chrome/browser/media/router/media_route_id.h
new file mode 100644
index 0000000000000000000000000000000000000000..7657702da3f4869119fe61186753da60d7b19225
--- /dev/null
+++ b/chrome/browser/media/router/media_route_id.h
@@ -0,0 +1,18 @@
+// Copyright 2015 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_ID_H_
+#define CHROME_BROWSER_MEDIA_ROUTER_MEDIA_ROUTE_ID_H_
+
+#include <string>
+
+#include "base/callback.h"
+
+namespace media_router {
+
+typedef std::string MediaRouteId;

[mark a. foltz, 2015/03/02 21:40:09]

Any downside to placing this into media_route.h (or are there headers that need
only the id declared)?

[mark a. foltz, 2015/03/02 21:40:09]

using

[Kevin M, 2015/03/03 21:53:19]

A cycle is introduced if we fold media_route_id.h into media_route.h:

media_route.h --depends--> media_controller.h --depends--> media_route_id.h

+
+}  // namespace media_router
+
+#endif  // CHROME_BROWSER_MEDIA_ROUTER_MEDIA_ROUTE_ID_H_