Migrate stdlib task queue to TaskQueueBase interface

Bug: webrtc:10191
Change-Id: I16e13b69dce7cafa545977e9ac253b6e57312690
Reviewed-on: https://webrtc-review.googlesource.com/c/123760
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26796}

rtc_base/task_queue_stdlib.h

@@ -0,0 +1,24 @@
+/*
+ *  Copyright 2019 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef RTC_BASE_TASK_QUEUE_STDLIB_H_
+#define RTC_BASE_TASK_QUEUE_STDLIB_H_
+
+#include <memory>
+
+#include "api/task_queue/task_queue_factory.h"
+
+namespace webrtc {
+
+std::unique_ptr<TaskQueueFactory> CreateTaskQueueStdlibFactory();
+
+}  // namespace webrtc
+
+#endif  // RTC_BASE_TASK_QUEUE_STDLIB_H_