Ensures that audio tasks cannot run after AudioManager is deleted.

content/browser/audio_manager_thread.cc

-// Copyright 2016 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 "content/browser/audio_manager_thread.h"
-
-#include "base/threading/thread_task_runner_handle.h"
-#include "build/build_config.h"
-
-namespace content {
-
-AudioManagerThread::AudioManagerThread() : thread_("AudioThread") {
-#if defined(OS_WIN)
-  thread_.init_com_with_mta(true);
-#endif
-  CHECK(thread_.Start());
-
-#if defined(OS_MACOSX)
-  // On Mac, the audio task runner must belong to the main thread.
-  // See http://crbug.com/158170.
-  task_runner_ = base::ThreadTaskRunnerHandle::Get();
-#else
-  task_runner_ = thread_.task_runner();
-#endif
-}
-
-AudioManagerThread::~AudioManagerThread() {}
-
-}  // namespace content