Add media router common classes and unittests.

chrome/browser/media/router/media_cast_mode.h

+// Copyright 2014 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_CAST_MODE_H_
+#define CHROME_BROWSER_MEDIA_ROUTER_MEDIA_CAST_MODE_H_
+
+#include <string>
+
+namespace media_router {
+
+// Represents available cast modes.
+enum MediaCastMode {

[mark a. foltz, 2015/02/27 05:48:10]

Per discussion with imcheng@ today this is really something that is managed by
the UI, not the backend; I would prefer it live in the webui/folder (or a
separate component).

I would be inclined to leave it out of this patch until its eventual location is
set.

[Kevin M, 2015/02/27 18:42:17]

Done.

+  APP_CAST,
+  SCREEN_WINDOW_MIRROR,
+  SOUND_OPTIMIZED_TAB_MIRROR,
+  TAB_MIRROR,
+};
+
+std::string MediaCastModeToTitle(MediaCastMode mode);
+
+}  // namespace media_router
+
+#endif  // CHROME_BROWSER_MEDIA_ROUTER_MEDIA_CAST_MODE_H_