MediaStream audio sourcing: Bypass audio processing for non-WebRTC cases.

content/renderer/media/external_media_stream_audio_source.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 CONTENT_RENDERER_MEDIA_EXTERNAL_MEDIA_STREAM_AUDIO_SOURCE_H_
+#define CONTENT_RENDERER_MEDIA_EXTERNAL_MEDIA_STREAM_AUDIO_SOURCE_H_
+
+#include "content/renderer/media/media_stream_audio_source.h"
+
+#include "media/base/audio_capturer_source.h"
+
+namespace content {
+
+// Represents an externally-provided local or remote source of audio data.  This
+// allows users of the public content::MediaStreamApi to provide a
+// media::AudioCapturerSource to be used as the source of audio data in the
+// MediaStream framework.  Audio data is transported directly to the tracks
+// (i.e., there is no audio processing).
+class CONTENT_EXPORT ExternalMediaStreamAudioSource
+    : NON_EXPORTED_BASE(public MediaStreamAudioSource),
+      NON_EXPORTED_BASE(public media::AudioCapturerSource::CaptureCallback) {
+ public:
+  ExternalMediaStreamAudioSource(
+    const scoped_refptr<media::AudioCapturerSource>& source,
+    int sample_rate,
+    media::ChannelLayout channel_layout,
+    int frames_per_buffer,
+    bool is_remote);
+
+  ~ExternalMediaStreamAudioSource() final;
+
+ private:
+  // MediaStreamAudioSource implementation.
+  void DoStopSource() final;
+  bool EnsureSourceIsStarted() final;
+
+  // media::AudioCapturerSource::CaptureCallback implementation.
+  void Capture(const media::AudioBus* audio_bus,
+               int audio_delay_milliseconds,
+               double volume,
+               bool key_pressed) final;
+  void OnCaptureError(const std::string& message) final;
+
+  // The external source provided to the constructor.
+  const scoped_refptr<media::AudioCapturerSource> source_;
+
+  // True once the source has been started successfully.
+  bool is_started_;
+
+  DISALLOW_COPY_AND_ASSIGN(ExternalMediaStreamAudioSource);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_MEDIA_EXTERNAL_MEDIA_STREAM_AUDIO_SOURCE_H_