Unmute Tab Audio For Desktop Share

media/audio/virtual_audio_sink.h

+// Copyright 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.
+
+#ifndef MEDIA_AUDIO_VIRTUAL_AUDIO_SINK_H_
+#define MEDIA_AUDIO_VIRTUAL_AUDIO_SINK_H_
+
+#include "base/callback.h"
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "base/synchronization/lock.h"
+#include "media/audio/audio_io.h"
+#include "media/audio/audio_source_diverter.h"
+#include "media/base/audio_converter.h"
+#include "media/base/audio_shifter.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+}
+
+namespace media {
+
+class VirtualAudioInputStream;
+
+// This class is an adapter between push model and pull model for audio stream.

[DaleCurtis, 2016/06/01 20:58:07]

Since it has a lock explain threading rules.

[qiangchen, 2016/06/01 21:43:15]

Done.

+// Audio provider calls OnData() to push audio data into this class.
+// Audio consumer calls ProvideInput() to pull audio data.
+class MEDIA_EXPORT VirtualAudioSink
+    : public AudioPushSink,
+      public AudioConverter::InputCallback,
+      public base::SupportsWeakPtr<VirtualAudioSink> {

[DaleCurtis, 2016/06/01 20:58:07]

We don't tend to use SupportsWeakPtr; instead favoring a private weak factory,
do you really need this?

[qiangchen, 2016/06/01 21:43:15]

Done.

+ public:
+  typedef base::Callback<void(VirtualAudioSink* sink)> AfterCloseCallback;
+
+  // Construct an audio loopback pathway to the given |target| (not owned).
+  // |target| must outlive this instance.
+  VirtualAudioSink(AudioParameters param,

[DaleCurtis, 2016/06/01 20:58:07]

const&

[qiangchen, 2016/06/01 21:43:15]

Done.

+                   VirtualAudioInputStream* target,
+                   AfterCloseCallback callback);

[DaleCurtis, 2016/06/01 20:58:07]

const&

[qiangchen, 2016/06/01 21:43:15]

Done.

+  ~VirtualAudioSink() override;
+
+  // AudioPushSink
+  void Close() override;
+  void OnData(std::unique_ptr<AudioBus> source,
+              base::TimeTicks reference_time) override;
+
+  // AudioConverter::InputCallback
+  double ProvideInput(AudioBus* audio_bus, uint32_t frames_delayed) override;
+
+ private:
+  void StoreData(AudioBus* source, base::TimeTicks reference_time);
+
+  const AudioParameters params_;
+  VirtualAudioInputStream* const target_;
+  AudioShifter shifter_;
+  base::Lock shifter_lock_;
+  AfterCloseCallback after_close_callback_;
+};

[DaleCurtis, 2016/06/01 20:58:07]

DISALLOW_COPY_AND_ASSIGN?

[qiangchen, 2016/06/01 21:43:15]

Done.

+
+}  // namespace media
+
+#endif  // MEDIA_AUDIO_VIRTUAL_AUDIO_SINK_H_