Ensures that audio tasks cannot run after AudioManager is deleted.

media/audio/test_audio_thread.cc

Index: media/audio/test_audio_thread.cc
diff --git a/media/audio/test_audio_thread.cc b/media/audio/test_audio_thread.cc
new file mode 100644
index 0000000000000000000000000000000000000000..432753571457ac1f1718649efaae3dac45e6fcd2
--- /dev/null
+++ b/media/audio/test_audio_thread.cc
@@ -0,0 +1,33 @@
+// Copyright 2017 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 "media/audio/test_audio_thread.h"
+
+#include "base/run_loop.h"
+#include "base/threading/thread_task_runner_handle.h"
+
+namespace media {
+
+TestAudioThread::TestAudioThread()
+    : task_runner_(base::ThreadTaskRunnerHandle::Get()) {}

[o1ka, 2017/04/28 13:24:20]

The purpose of this class needs to be explained in the header. Otherwise it's
too tempting to use it for all tests, but some cases do require a separate audio
thread to be tested properly.

Actually, I would prefer to avoid having this test class. Can we pass "use
current task runner" flag into the constructor of AudioThread?

[alokp, 2017/04/28 17:31:13]

I will add more comments. IMO having this separate from the main implementation
is cleaner.

[o1ka, 2017/05/02 16:16:01]

See my comment in audio_system_impl_unittest.cc. AudioThreadImpl +
TestAudioThread do not cover everything we need. We want to be able to specify
threading for tests in a platform-independent way.

[alokp, 2017/05/09 19:06:15]

Done.

+
+TestAudioThread::~TestAudioThread() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+}
+
+void TestAudioThread::Stop() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  base::RunLoop().RunUntilIdle();
+  task_runner_ = nullptr;
+}
+
+base::SingleThreadTaskRunner* TestAudioThread::GetTaskRunner() {
+  return task_runner_.get();
+}
+
+base::SingleThreadTaskRunner* TestAudioThread::GetWorkerTaskRunner() {
+  return task_runner_.get();
+}
+
+}  // namespace media