[Media Router] Remove RouteIDManager.

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