Add media router common classes and unittests.

chrome/browser/media/router/route_id_manager_unittest.cc

+// 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.
+
+#include "chrome/browser/media/router/route_id_manager.h"
+#include "testing/gmock/include/gmock/gmock.h"
+
+namespace media_router {
+
+TEST(RouteIDManagerTest, ForLocalRoute) {
+  // Singleton instance is left unused for better test isolation.
+  RouteIDManager manager1;
+  EXPECT_EQ("route-local-0", manager1.ForLocalRoute());
+  EXPECT_EQ("route-local-1", manager1.ForLocalRoute());
+
+  RouteIDManager manager2;
+  EXPECT_EQ("route-local-0", manager2.ForLocalRoute());
+}
+
+}  // namespace media_router