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(
+    AudioManager* audio_manager,
+    scoped_refptr<base::SingleThreadTaskRunner> task_runner)
+    : audio_manager_(audio_manager),
+      task_runner_(std::move(task_runner)),
+      weak_factory_(this) {
+  DCHECK(audio_manager_);
+}
+
+AudioDebugRecordingHelper::~AudioDebugRecordingHelper() {}
+
+void AudioDebugRecordingHelper::EnableDebugRecording(
+    const AudioParameters& params,
+    const base::FilePath& file_name) {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  DCHECK(!debug_writer_);
+
+  debug_writer_ = audio_manager_->CreateAudioFileWriter(params);

[o1ka, 2017/01/20 11:36:26]

This is an unfortunate dependency on AudioManager. Creating file writer has
nothing to do with audio system. Could you pass a callback in
AudioDebugRecordingHelper constructor instead?

[Henrik Grunell, 2017/01/26 10:25:09]

Done.

+
+  // The debug writer writes in wave format.
+  debug_writer_->Start(file_name.AddExtension("wav"));
+}
+
+void AudioDebugRecordingHelper::DisableDebugRecording() {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+
+  if (debug_writer_) {
+    debug_writer_->Stop();
+    debug_writer_.reset();
+  }
+}
+
+void AudioDebugRecordingHelper::MaybeWrite(const AudioBus* source) {
+  if (!WillWrite())
+    return;
+
+  // TODO(grunell) Don't create a new AudioBus each time. Maybe a pool of
+  // AudioBuses. See also AudioInputController.
+  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)));

[o1ka, 2017/01/20 11:36:26]

Can you have one pre-created weak pointer and reuse it all over?

[Henrik Grunell, 2017/01/26 10:25:09]

I haven't seen it used that way, have you? Doesn't Bind take ownership and
release the reference?

+}
+
+bool AudioDebugRecordingHelper::WillWrite() {
+  return debug_writer_ && debug_writer_->WillWrite();

[o1ka, 2017/01/20 11:36:26]

Add a comment on why it's thread-safe enough?

[Henrik Grunell, 2017/01/26 10:25:09]

Done. Both here and in header.

+}
+
+void AudioDebugRecordingHelper::DoWrite(std::unique_ptr<media::AudioBus> data) {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+
+  if (debug_writer_)
+    debug_writer_->Write(std::move(data));
+}
+
+}  // namspace media