[Media Router] Remove RouteIDManager.

chrome/browser/media/router/route_id_manager.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 "base/memory/singleton.h"
-#include "base/strings/string_number_conversions.h"
-#include "chrome/browser/media/router/media_route.h"
-
-namespace media_router {
-
-const char kLocalRoutePrefix[] = "route-local-";
-
-RouteIDManager::RouteIDManager() : next_local_id_(0) {}
-
-std::string RouteIDManager::ForLocalRoute() {
-  DCHECK(CalledOnValidThread());
-  return kLocalRoutePrefix + base::Uint64ToString(next_local_id_++);
-}
-
-// static
-RouteIDManager* RouteIDManager::GetInstance() {
-  return Singleton<RouteIDManager>::get();
-}
-
-}  // namespace media_router