Add the copresence DirectiveHandler.

components/copresence/mediums/audio/audio_player.cc

Index: components/copresence/mediums/audio/audio_player.cc
diff --git a/components/copresence/mediums/audio/audio_player.cc b/components/copresence/mediums/audio/audio_player.cc
new file mode 100644
index 0000000000000000000000000000000000000000..723b905f8906fd6ad382d24808a77d5c24879fcc
--- /dev/null
+++ b/components/copresence/mediums/audio/audio_player.cc
@@ -0,0 +1,185 @@
+// Copyright 2014 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 "components/copresence/mediums/audio/audio_player.h"
+
+#include <algorithm>
+#include <vector>
+
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/logging.h"
+#include "base/run_loop.h"
+#include "components/copresence/public/copresence_constants.h"
+#include "content/public/browser/browser_thread.h"
+#include "media/audio/audio_manager.h"
+#include "media/audio/audio_parameters.h"
+#include "media/base/audio_bus.h"
+
+namespace {
+
+const int kDefaultFrameCount = 1024;
+const double kOutputVolumePercent = 1.0f;
+
+}  // namespace
+
+namespace copresence {
+
+// Public methods.
+
+AudioPlayer::AudioPlayer()
+    : stream_(NULL), is_playing_(false), frame_index_(0) {
+}
+
+AudioPlayer::~AudioPlayer() {
+}
+
+void AudioPlayer::Initialize() {
+  media::AudioManager::Get()->GetTaskRunner()->PostTask(
+      FROM_HERE,
+      base::Bind(&AudioPlayer::InitializeOnAudioThread,
+                 base::Unretained(this)));
+}
+
+void AudioPlayer::Play(
+    const scoped_refptr<media::AudioBusRefCounted>& samples) {
+  media::AudioManager::Get()->GetTaskRunner()->PostTask(
+      FROM_HERE,
+      base::Bind(
+          &AudioPlayer::PlayOnAudioThread, base::Unretained(this), samples));
+}
+
+void AudioPlayer::Stop() {
+  media::AudioManager::Get()->GetTaskRunner()->PostTask(
+      FROM_HERE,
+      base::Bind(&AudioPlayer::StopOnAudioThread, base::Unretained(this)));
+}
+
+void AudioPlayer::Finalize() {
+  media::AudioManager::Get()->GetTaskRunner()->PostTask(
+      FROM_HERE,
+      base::Bind(&AudioPlayer::FinalizeOnAudioThread, base::Unretained(this)));
+}
+
+// Private methods.
+
+void AudioPlayer::InitializeOnAudioThread() {
+  DCHECK(media::AudioManager::Get()->GetTaskRunner()->BelongsToCurrentThread());
+  stream_ = output_stream_for_testing_
+                ? output_stream_for_testing_.get()
+                : media::AudioManager::Get()->MakeAudioOutputStreamProxy(
+                      media::AudioParameters(
+                          media::AudioParameters::AUDIO_PCM_LOW_LATENCY,
+                          media::CHANNEL_LAYOUT_MONO,
+                          kDefaultSampleRate,
+                          kDefaultBitsPerSample,
+                          kDefaultFrameCount),
+                      std::string());
+
+  if (!stream_ || !stream_->Open()) {
+    LOG(ERROR) << "Failed to open an output stream.";
+    if (stream_) {
+      stream_->Close();
+      stream_ = NULL;
+    }
+    return;
+  }
+  stream_->SetVolume(kOutputVolumePercent);
+}
+
+void AudioPlayer::PlayOnAudioThread(
+    const scoped_refptr<media::AudioBusRefCounted>& samples) {
+  DCHECK(media::AudioManager::Get()->GetTaskRunner()->BelongsToCurrentThread());
+  if (!stream_)
+    return;
+
+  {
+    base::AutoLock al(state_lock_);
+
+    samples_ = samples;
+    frame_index_ = 0;
+
+    if (is_playing_)
+      return;
+  }
+
+  DVLOG(2) << "Playing Audio.";
+  is_playing_ = true;

[Daniel Erat, 2014/08/05 16:38:52]

you have an unprotected write to is_playing_ here (and in a bunch of other audio
thread methods), but OnMoreData() reads is_playing_ and is documented as
potentially being called from any thread. should is_playing_ be protected by the
lock as well?

[rkc, 2014/08/05 18:00:35]

This lock is in place to prevent simultaneous read/write to the actual audio
data and the frame pointer into it. OnMoreData doesn't actually need to even
check is_playing_ except for the DCHECK. The DCHECK isn't super useful as the
audio code is supposed to ensure that OnMoreData isn't called after we stop the
stream. Removing the DCHECK removes this concern completely.

Done.

+  stream_->Start(this);
+}
+
+void AudioPlayer::StopOnAudioThread() {
+  DCHECK(media::AudioManager::Get()->GetTaskRunner()->BelongsToCurrentThread());
+  if (!stream_)
+    return;
+
+  stream_->Stop();
+  is_playing_ = false;
+}
+
+void AudioPlayer::StopAndCloseOnAudioThread() {
+  DCHECK(media::AudioManager::Get()->GetTaskRunner()->BelongsToCurrentThread());
+  if (!stream_)
+    return;
+
+  if (is_playing_)
+    stream_->Stop();
+  stream_->Close();
+  stream_ = NULL;
+
+  is_playing_ = false;
+}
+
+void AudioPlayer::FinalizeOnAudioThread() {
+  DCHECK(media::AudioManager::Get()->GetTaskRunner()->BelongsToCurrentThread());
+  StopAndCloseOnAudioThread();
+  delete this;
+}
+
+int AudioPlayer::OnMoreData(media::AudioBus* dest,
+                            media::AudioBuffersState /* state */) {
+  base::AutoLock al(state_lock_);
+  DCHECK(is_playing_);
+
+  // Continuously play our samples till explicitly told to stop.
+  const int leftover_frames = samples_->frames() - frame_index_;
+  const int frames_to_copy = std::min(dest->frames(), leftover_frames);
+
+  samples_->CopyPartialFramesTo(frame_index_, frames_to_copy, 0, dest);
+  frame_index_ += frames_to_copy;
+
+  // If we didn't fill the destination audio bus, wrap around and fill the rest.
+  if (leftover_frames <= dest->frames()) {
+    samples_->CopyPartialFramesTo(
+        0, dest->frames() - frames_to_copy, frames_to_copy, dest);
+    frame_index_ = dest->frames() - frames_to_copy;
+  }
+
+  return dest->frames();
+}
+
+void AudioPlayer::OnError(media::AudioOutputStream* /* stream */) {
+  LOG(ERROR) << "Error during system sound reproduction.";
+  media::AudioManager::Get()->GetTaskRunner()->PostTask(
+      FROM_HERE,
+      base::Bind(&AudioPlayer::StopAndCloseOnAudioThread,
+                 base::Unretained(this)));
+}
+
+void AudioPlayer::FlushAudioLoopForTesting() {
+  if (media::AudioManager::Get()->GetTaskRunner()->BelongsToCurrentThread())
+    return;
+
+  // Queue task on the audio thread, when it is executed, that means we've
+  // successfully executed all the tasks before us.
+  base::RunLoop rl;
+  media::AudioManager::Get()->GetTaskRunner()->PostTaskAndReply(
+      FROM_HERE,
+      base::Bind(base::IgnoreResult(&AudioPlayer::FlushAudioLoopForTesting),
+                 base::Unretained(this)),
+      rl.QuitClosure());
+  rl.Run();
+}
+
+}  // namespace copresence