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_IMAGE_CAPTURE_FRAME_GRABBER_H_
-#define CONTENT_RENDERER_MEDIA_IMAGE_CAPTURE_FRAME_GRABBER_H_
+#ifndef CONTENT_RENDERER_MEDIA_EXTERNAL_MEDIA_STREAM_AUDIO_SOURCE_H_
+#define CONTENT_RENDERER_MEDIA_EXTERNAL_MEDIA_STREAM_AUDIO_SOURCE_H_
 
-#include "base/compiler_specific.h"
-#include "base/macros.h"
-#include "base/memory/weak_ptr.h"
-#include "base/threading/thread_checker.h"
-#include "content/child/scoped_web_callbacks.h"
-#include "content/common/content_export.h"
-#include "content/public/renderer/media_stream_video_sink.h"
-#include "third_party/WebKit/public/platform/WebImageCaptureFrameGrabber.h"
+#include "content/renderer/media/media_stream_audio_source.h"
 
-namespace blink {
-class WebMediaStreamTrack;
-}
-
-namespace media {
-class VideoFrame;
-}
+#include "media/base/audio_capturer_source.h"
 
 namespace content {
 
-// This class grabs Video Frames from a given Media Stream Video Track, binding
-// a function every time grabFrame() is called. This function receives an
-// incoming VideoFrame on a background thread and converts it into the
-// appropriate SkBitmap which is sent back to OnSkBitmap(). This class is single
-// threaded throughout.
-class CONTENT_EXPORT ImageCaptureFrameGrabber final
-    : NON_EXPORTED_BASE(public blink::WebImageCaptureFrameGrabber),
-      NON_EXPORTED_BASE(public MediaStreamVideoSink) {
+// 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:
-  using SkImageDeliverCB = base::Callback<void(sk_sp<SkImage>)>;
+  ExternalMediaStreamAudioSource(
+      scoped_refptr<media::AudioCapturerSource> source,
+      int sample_rate,
+      media::ChannelLayout channel_layout,
+      int frames_per_buffer,
+      bool is_remote);
 
-  ImageCaptureFrameGrabber();
-  ~ImageCaptureFrameGrabber() override;
-
-  // blink::WebImageCaptureFrameGrabber implementation.
-  void grabFrame(blink::WebMediaStreamTrack* track,
-                 blink::WebImageCaptureGrabFrameCallbacks* callbacks) override;
+  ~ExternalMediaStreamAudioSource() final;
 
  private:
-  void OnSkImage(
-      ScopedWebCallbacks<blink::WebImageCaptureGrabFrameCallbacks> callbacks,
-      sk_sp<SkImage> image);
+  // 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_;
-  base::WeakPtrFactory<ImageCaptureFrameGrabber> weak_factory_;
 
-  DISALLOW_COPY_AND_ASSIGN(ImageCaptureFrameGrabber);
+  // True once the source has been started successfully.
+  bool was_started_;
+
+  DISALLOW_COPY_AND_ASSIGN(ExternalMediaStreamAudioSource);
 };
 
 }  // namespace content
 
-#endif  // CONTENT_RENDERER_MEDIA_IMAGE_CAPTURE_FRAME_GRABBER_H_
+#endif  // CONTENT_RENDERER_MEDIA_EXTERNAL_MEDIA_STREAM_AUDIO_SOURCE_H_