Unmute Tab Audio For Desktop Share

media/audio/virtual_audio_sink.cc

Index: media/audio/virtual_audio_sink.cc
diff --git a/media/audio/virtual_audio_sink.cc b/media/audio/virtual_audio_sink.cc
new file mode 100644
index 0000000000000000000000000000000000000000..d870d303ae14a51e752b25aa0f5622e2dbf75847
--- /dev/null
+++ b/media/audio/virtual_audio_sink.cc
@@ -0,0 +1,60 @@
+// Copyright (c) 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 "media/audio/virtual_audio_sink.h"
+
+#include "media/audio/virtual_audio_input_stream.h"
+
+namespace media {
+
+static const base::TimeDelta kBufferSize = base::TimeDelta::FromSeconds(1);
+static const base::TimeDelta kClockAccuracy =
+    base::TimeDelta::FromMilliseconds(1);
+static const base::TimeDelta kAdjustTime = base::TimeDelta::FromSeconds(1);
+
+VirtualAudioSink::VirtualAudioSink(AudioParameters param,
+                                   VirtualAudioInputStream* target,
+                                   AfterCloseCallback callback)
+    : started_(false),
+      params_(param),
+      target_(target),
+      shifter_(new AudioShifter(kBufferSize,
+                                kClockAccuracy,
+                                kAdjustTime,
+                                param.sample_rate(),
+                                param.channels())),
+      after_close_callback_(callback) {}
+
+VirtualAudioSink::~VirtualAudioSink() {}
+
+void VirtualAudioSink::Start() {
+  started_ = true;
+  target_->AddOutputStream(this, params_);
+}
+
+void VirtualAudioSink::Stop() {
+  target_->RemoveOutputStream(this, params_);
+  started_ = false;
+}
+
+void VirtualAudioSink::Close() {
+  if (started_)
+    Stop();
+  AfterCloseCallback cb = after_close_callback_;

[miu, 2016/04/21 00:15:25]

nit: The rest of this method should be (using existing Chromium constructs):

  if (!after_close_callback_.is_null())
    base::ResetAndReturn(&after_close_callback_).Run();

[qiangchen, 2016/04/28 00:00:56]

Done.

+  if (!cb.is_null())
+    cb.Run(this);
+}
+
+void VirtualAudioSink::OnData(const AudioBus* source) {
+  std::unique_ptr<AudioBus> source_copy = AudioBus::Create(params_);
+  source->CopyTo(source_copy.get());
+  shifter_->Push(std::move(source_copy), base::TimeTicks::Now());
+}
+
+double VirtualAudioSink::ProvideInput(AudioBus* audio_bus,
+                                      base::TimeDelta buffer_delay) {
+  shifter_->Pull(audio_bus, base::TimeTicks::Now());

[miu, 2016/04/21 00:15:25]

|buffer_delay| must be accounted for in the second argument to Pull() here.

[qiangchen, 2016/04/28 00:00:56]

Done.

+  return 1;
+}
+}