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

content/renderer/media/webaudio_capturer_source.h

+// Copyright (c) 2012 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_WEBAUDIO_CAPTURER_SOURCE_H_
+#define CONTENT_RENDERER_MEDIA_WEBAUDIO_CAPTURER_SOURCE_H_
+
+#include <stddef.h>
+
+#include "base/macros.h"
+#include "base/synchronization/lock.h"
+#include "base/threading/thread_checker.h"
+#include "base/time/time.h"
+#include "media/base/audio_bus.h"
+#include "media/base/audio_capturer_source.h"
+#include "media/base/audio_parameters.h"
+#include "media/base/audio_push_fifo.h"
+#include "third_party/WebKit/public/platform/WebAudioDestinationConsumer.h"
+#include "third_party/WebKit/public/platform/WebMediaStreamSource.h"
+#include "third_party/WebKit/public/platform/WebVector.h"
+
+namespace content {
+
+class WebRtcLocalAudioTrack;
+
+// WebAudioCapturerSource is the missing link between
+// WebAudio's MediaStreamAudioDestinationNode and WebRtcLocalAudioTrack.
+//
+// 1. WebKit calls the setFormat() method setting up the basic stream format
+//    (channels, and sample-rate).
+// 2. consumeAudio() is called periodically by WebKit which dispatches the
+//    audio stream to the WebRtcLocalAudioTrack::Capture() method.
+class WebAudioCapturerSource : public blink::WebAudioDestinationConsumer {
+ public:
+  explicit WebAudioCapturerSource(blink::WebMediaStreamSource* blink_source);
+
+  ~WebAudioCapturerSource() override;
+
+  // WebAudioDestinationConsumer implementation.
+  // setFormat() is called early on, so that we can configure the audio track.
+  void setFormat(size_t number_of_channels, float sample_rate) override;
+  // MediaStreamAudioDestinationNode periodically calls consumeAudio().
+  // Called on the WebAudio audio thread.
+  void consumeAudio(const blink::WebVector<const float*>& audio_data,
+                    size_t number_of_frames) override;
+
+  // Called when the WebAudioCapturerSource is hooking to a media audio track.
+  // |track| is the sink of the data flow and must remain alive until Stop() is
+  // called.
+  void Start(WebRtcLocalAudioTrack* track);
+
+  // Called when the media audio track is stopping.
+  void Stop();
+
+ private:
+  // Called by AudioPushFifo zero or more times during the call to
+  // consumeAudio().  Delivers audio data with the required buffer size to the
+  // track.
+  void DeliverRebufferedAudio(const media::AudioBus& audio_bus,
+                              int frame_delay);
+
+  // Deregisters this object from its blink::WebMediaStreamSource.
+  void DeregisterFromBlinkSource();
+
+  // Used to DCHECK that some methods are called on the correct thread.
+  base::ThreadChecker thread_checker_;
+
+  // The audio track this WebAudioCapturerSource is feeding data to.
+  WebRtcLocalAudioTrack* track_;
+
+  media::AudioParameters params_;
+
+  // Flag to help notify the |track_| when the audio format has changed.
+  bool audio_format_changed_;
+
+  // A wrapper used for providing audio to |fifo_|.
+  std::unique_ptr<media::AudioBus> wrapper_bus_;
+
+  // Takes in the audio data passed to consumeAudio() and re-buffers it into 10
+  // ms chunks for the track.  This ensures each chunk of audio delivered to the
+  // track has the required buffer size, regardless of the amount of audio
+  // provided via each consumeAudio() call.
+  media::AudioPushFifo fifo_;
+
+  // Used to pass the reference timestamp between DeliverDecodedAudio() and
+  // DeliverRebufferedAudio().
+  base::TimeTicks current_reference_time_;
+
+  // Synchronizes HandleCapture() with AudioCapturerSource calls.
+  base::Lock lock_;
+
+  // This object registers with a blink::WebMediaStreamSource. We keep track of
+  // that in order to be able to deregister before stopping the audio track.
+  blink::WebMediaStreamSource blink_source_;
+
+  DISALLOW_COPY_AND_ASSIGN(WebAudioCapturerSource);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_MEDIA_WEBAUDIO_CAPTURER_SOURCE_H_