Add media router common classes and unittests.

chrome/browser/media/router/route_id_manager.h

+// 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.
+
+#ifndef CHROME_BROWSER_MEDIA_ROUTER_ROUTE_ID_MANAGER_H_
+#define CHROME_BROWSER_MEDIA_ROUTER_ROUTE_ID_MANAGER_H_
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/gtest_prod_util.h"
+#include "base/memory/singleton.h"
+#include "base/threading/non_thread_safe.h"
+
+namespace media_router {
+
+class MediaRoute;
+
+// Shared singleton which coordinates the assignment of unique IDs to
+// MediaRoute objects.
+class RouteIDManager : public base::NonThreadSafe {

[xhwang, 2015/03/10 04:27:07]

Is NonThreadSafe needed? You are not checking CalledOnValidThread()...

[Kevin M, 2015/03/10 17:40:04]

An omission that crept in when I rewrote this from the previous factory impl.
Fixed, thanks.

+ public:
+  static RouteIDManager* GetInstance();
+
+  std::string ForLocalRoute();
+
+ private:
+  FRIEND_TEST_ALL_PREFIXES(RouteIDManagerTest, ForLocalRoute);
+  friend struct DefaultSingletonTraits<RouteIDManager>;
+
+  RouteIDManager();
+
+  // Monotonically increasing ID number.
+  uint64 next_local_id_;
+
+  DISALLOW_COPY_AND_ASSIGN(RouteIDManager);
+};
+
+}  // namespace media_router
+
+#endif  // CHROME_BROWSER_MEDIA_ROUTER_ROUTE_ID_MANAGER_H_