Add media router common classes and unittests.

chrome/browser/media/router/media_cast_mode.cc

Index: chrome/browser/media/router/media_cast_mode.cc
diff --git a/chrome/browser/media/router/media_cast_mode.cc b/chrome/browser/media/router/media_cast_mode.cc
new file mode 100644
index 0000000000000000000000000000000000000000..e5d660531b50ae7d22b8ef09d0b5e432694a2f49
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+++ b/chrome/browser/media/router/media_cast_mode.cc
@@ -0,0 +1,28 @@
+// 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.
+
+#include "chrome/browser/media/router/media_cast_mode.h"
+
+#include "base/logging.h"
+
+namespace media_router {
+
+// TODO(haibinlu): use localized string.
+std::string MediaCastModeToTitle(MediaCastMode mode) {
+  switch (mode) {
+    case MediaCastMode::APP_CAST:
+      return "Cast [website here]";
+    case MediaCastMode::SCREEN_WINDOW_MIRROR:
+      return "Cast screen/window";
+    case MediaCastMode::SOUND_OPTIMIZED_TAB_MIRROR:
+      return "Cast this tab (optimize for audio)";
+    case MediaCastMode::TAB_MIRROR:
+      return "Cast this tab";
+    default:
+      NOTREACHED();
+      return "";
+  }
+}
+
+}  // namespace media_router