Revert of MediaStream audio: Refactor 3 separate "glue" implementations into one.

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 final
-    : NON_EXPORTED_BASE(public MediaStreamAudioSource),
-      NON_EXPORTED_BASE(public media::AudioCapturerSource::CaptureCallback) {
- public:
-  ExternalMediaStreamAudioSource(
-      scoped_refptr<media::AudioCapturerSource> source,
-      int sample_rate,
-      media::ChannelLayout channel_layout,
-      int frames_per_buffer,
-      bool is_remote);
-
-  ~ExternalMediaStreamAudioSource() final;
-
- private:
-  // MediaStreamAudioSource implementation.
-  bool EnsureSourceIsStarted() final;
-  void EnsureSourceIsStopped() 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.
-  scoped_refptr<media::AudioCapturerSource> source_;
-
-  // In debug builds, check that all methods that could cause object graph
-  // or data flow changes are being called on the main thread.
-  base::ThreadChecker thread_checker_;
-
-  // True once the source has been started successfully.
-  bool was_started_;
-
-  DISALLOW_COPY_AND_ASSIGN(ExternalMediaStreamAudioSource);
-};
-
-}  // namespace content
-
-#endif  // CONTENT_RENDERER_MEDIA_EXTERNAL_MEDIA_STREAM_AUDIO_SOURCE_H_