Audio output debug recording.

media/audio/audio_debug_recording_helper.cc

+// 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/audio_debug_recording_helper.h"
+
+#include "base/bind.h"
+#include "base/files/file_path.h"
+#include "base/single_thread_task_runner.h"
+#include "media/audio/audio_manager.h"
+
+namespace media {
+
+AudioDebugRecordingHelper::AudioDebugRecordingHelper(
+    const AudioParameters& params,
+    const CreateAudioFileWriterCallback& create_audio_file_writer_callback,
+    scoped_refptr<base::SingleThreadTaskRunner> task_runner,
+    base::OnceClosure on_destruction_closure)
+    : params_(params),
+      create_audio_file_writer_callback_(create_audio_file_writer_callback),
+      task_runner_(std::move(task_runner)),
+      on_destruction_closure_(std::move(on_destruction_closure)),
+      weak_factory_(this) {
+  DCHECK(create_audio_file_writer_callback_);
+}
+
+AudioDebugRecordingHelper::~AudioDebugRecordingHelper() {
+  if (on_destruction_closure_)
+    std::move(on_destruction_closure_).Run();
+}
+
+void AudioDebugRecordingHelper::EnableDebugRecording(
+    const base::FilePath& file_name) {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  DCHECK(!debug_writer_);
+
+  debug_writer_ = create_audio_file_writer_callback_.Run(params_);
+
+  // The debug writer writes in wave format.

[o1ka, 2017/01/31 11:00:11]

How do we know it here? It's just some audio file writer. The extension should
be set externally by someone who knows what file writer it is.

[Henrik Grunell, 2017/02/08 11:29:37]

Agree. Added AudioFileWriter::GetExtension(), and implementation of it in
AudioDebugFileWriter. Currently, it's only the writer that knows about that. I
also updated the documentaion of AudioDebugFileWriter to say that it records a
16 bit PCM WAVE file.

+  debug_writer_->Start(file_name.AddExtension("wav"));
+}
+
+void AudioDebugRecordingHelper::DisableDebugRecording() {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+
+  if (debug_writer_) {
+    debug_writer_->Stop();
+    debug_writer_.reset();
+  }
+}
+
+bool AudioDebugRecordingHelper::WillWrite() {
+  // AudioFileWriter::WillWrite() can be called on any thread.

[o1ka, 2017/01/31 11:00:11]

Please explain why this method is ok to call from any thread, though it's not
thread-safe.

[Henrik Grunell, 2017/02/08 11:29:37]

Removed this function.

+  return debug_writer_ && debug_writer_->WillWrite();
+}
+
+void AudioDebugRecordingHelper::OnData(const AudioBus* source) {
+  if (!WillWrite())

[o1ka, 2017/01/31 11:00:11]

Why is it safe to call it here?

[Henrik Grunell, 2017/02/08 11:29:37]

WillWrite() has been removed, and I just check |debug_writer_| here instead
because WillWrite() is unecessary anyway. (It would have been safe but even
safer this way for the future.) Added comment about this.

+    return;
+
+  // TODO(grunell) Don't create a new AudioBus each time. Maybe a pool of
+  // AudioBuses. See also AudioInputController.

[o1ka, 2017/01/31 11:00:11]

What exactly in AudioInputController?

[Henrik Grunell, 2017/02/08 11:29:37]

Updated comment.

+  std::unique_ptr<AudioBus> audio_bus_copy =
+      AudioBus::Create(source->channels(), source->frames());
+  source->CopyTo(audio_bus_copy.get());
+
+  task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&AudioDebugRecordingHelper::DoWrite,
+                 weak_factory_.GetWeakPtr(), base::Passed(&audio_bus_copy)));
+}
+
+void AudioDebugRecordingHelper::DoWrite(std::unique_ptr<media::AudioBus> data) {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+
+  if (debug_writer_)
+    debug_writer_->Write(std::move(data));
+}
+
+}  // namespace media