Move scoped_test_dir.* and test_io_thread.* from edk/test to edk/system/test.

mojo/edk/test/test_io_thread.h

-// Copyright 2013 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 MOJO_EDK_TEST_TEST_IO_THREAD_H_
-#define MOJO_EDK_TEST_TEST_IO_THREAD_H_
-
-#include "base/callback_forward.h"
-#include "base/memory/ref_counted.h"
-#include "base/task_runner.h"
-#include "base/threading/thread.h"
-#include "mojo/public/cpp/system/macros.h"
-
-namespace mojo {
-namespace test {
-
-// Class to help create/run threads with I/O |MessageLoop|s in tests.
-class TestIOThread {
- public:
-  enum class StartMode { AUTO, MANUAL };
-  explicit TestIOThread(StartMode start_mode);
-  // Stops the I/O thread if necessary.
-  ~TestIOThread();
-
-  // |Start()|/|Stop()| should only be called from the main (creation) thread.
-  // After |Stop()|, |Start()| may be called again to start a new I/O thread.
-  // |Stop()| may be called even when the I/O thread is not started.
-  void Start();
-  void Stop();
-
-  // Post |task| to the IO thread.
-  void PostTask(const base::Closure& task);
-  // Posts |task| to the IO-thread with an WaitableEvent associated blocks on
-  // it until the posted |task| is executed, then returns.
-  void PostTaskAndWait(const base::Closure& task);
-
-  base::MessageLoopForIO* message_loop() {
-    return static_cast<base::MessageLoopForIO*>(io_thread_.message_loop());
-  }
-
-  scoped_refptr<base::SingleThreadTaskRunner> task_runner() {
-    return message_loop()->task_runner();
-  }
-
- private:
-  base::Thread io_thread_;
-  bool io_thread_started_;
-
-  MOJO_DISALLOW_COPY_AND_ASSIGN(TestIOThread);
-};
-
-}  // namespace test
-}  // namespace mojo
-
-#endif  // MOJO_EDK_TEST_TEST_IO_THREAD_H_