WebRtcMediaStreamTrackAdapter, maps 1 webrtc and 1 blink track

content/renderer/media/remote_media_stream_track_adapter.h

+// Copyright (c) 2017 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_REMOTE_MEDIA_TRACK_ADAPTER_H_
+#define CONTENT_RENDERER_MEDIA_REMOTE_MEDIA_TRACK_ADAPTER_H_
+
+#include <string>
+
+#include "base/bind.h"
+#include "base/callback_forward.h"
+#include "base/logging.h"
+#include "base/memory/ref_counted.h"
+#include "base/single_thread_task_runner.h"
+#include "third_party/WebKit/public/platform/WebMediaStreamSource.h"
+#include "third_party/WebKit/public/platform/WebMediaStreamTrack.h"
+#include "third_party/webrtc/api/mediastreaminterface.h"
+
+namespace content {
+
+class TrackObserver;
+
+// Base class used for mapping between webrtc and blink MediaStream tracks.
+// RemoteMediaStreamImpl has a RemoteMediaStreamTrackAdapter per remote audio
+// (RemoteAudioTrackAdapter) and video (RemoteVideoTrackAdapter) track.
+template <typename WebRtcMediaStreamTrackType>
+class RemoteMediaStreamTrackAdapter
+    : public base::RefCountedThreadSafe<
+          RemoteMediaStreamTrackAdapter<WebRtcMediaStreamTrackType>> {
+ public:
+  RemoteMediaStreamTrackAdapter(
+      const scoped_refptr<base::SingleThreadTaskRunner>& main_thread,
+      WebRtcMediaStreamTrackType* webrtc_track)
+      : main_thread_(main_thread),
+        webrtc_track_(webrtc_track),
+        id_(webrtc_track->id()) {}
+
+  const scoped_refptr<WebRtcMediaStreamTrackType>& observed_track() {
+    return webrtc_track_;
+  }
+
+  blink::WebMediaStreamTrack* web_track() {
+    DCHECK(main_thread_->BelongsToCurrentThread());
+    DCHECK(!web_track_.IsNull());
+    return &web_track_;
+  }
+
+  const std::string& id() const { return id_; }
+
+  bool initialized() const {
+    DCHECK(main_thread_->BelongsToCurrentThread());
+    return !web_track_.IsNull();
+  }
+
+  void Initialize() {
+    DCHECK(main_thread_->BelongsToCurrentThread());
+    DCHECK(!initialized());
+    web_initialize_.Run();
+    web_initialize_.Reset();
+    DCHECK(initialized());
+  }
+
+ protected:
+  friend class base::RefCountedThreadSafe<
+      RemoteMediaStreamTrackAdapter<WebRtcMediaStreamTrackType>>;
+
+  virtual ~RemoteMediaStreamTrackAdapter() {
+    DCHECK(main_thread_->BelongsToCurrentThread());
+  }
+
+  void InitializeWebTrack(blink::WebMediaStreamSource::Type type) {
+    DCHECK(main_thread_->BelongsToCurrentThread());
+    DCHECK(web_track_.IsNull());
+
+    blink::WebString web_track_id(blink::WebString::FromUTF8(id_));
+    blink::WebMediaStreamSource web_source;
+    web_source.Initialize(web_track_id, type, web_track_id, true /* remote */);
+    web_track_.Initialize(web_track_id, web_source);
+    DCHECK(!web_track_.IsNull());
+  }
+
+  const scoped_refptr<base::SingleThreadTaskRunner> main_thread_;
+  // This callback will be run when Initialize() is called and then freed.
+  // The callback is used by derived classes to bind objects that need to be
+  // instantiated and initialized on the signaling thread but then moved to
+  // and used on the main thread when initializing the web object(s).
+  base::Callback<void()> web_initialize_;
+
+ private:
+  const scoped_refptr<WebRtcMediaStreamTrackType> webrtc_track_;
+  blink::WebMediaStreamTrack web_track_;
+  // const copy of the webrtc track id that allows us to check it from both the
+  // main and signaling threads without incurring a synchronous thread hop.
+  const std::string id_;
+
+  DISALLOW_COPY_AND_ASSIGN(RemoteMediaStreamTrackAdapter);
+};
+
+class RemoteVideoTrackAdapter
+    : public RemoteMediaStreamTrackAdapter<webrtc::VideoTrackInterface> {
+ public:
+  // Called on the signaling thread.
+  RemoteVideoTrackAdapter(
+      const scoped_refptr<base::SingleThreadTaskRunner>& main_thread,
+      webrtc::VideoTrackInterface* webrtc_track);
+
+ protected:
+  ~RemoteVideoTrackAdapter() override;
+
+ private:
+  void InitializeWebVideoTrack(std::unique_ptr<TrackObserver> observer,
+                               bool enabled);
+};
+
+// RemoteAudioTrackAdapter is responsible for listening on state
+// change notifications on a remote webrtc audio MediaStreamTracks and notify
+// Blink.
+class RemoteAudioTrackAdapter
+    : public RemoteMediaStreamTrackAdapter<webrtc::AudioTrackInterface>,
+      public webrtc::ObserverInterface {
+ public:
+  // Called on the signaling thread.
+  RemoteAudioTrackAdapter(
+      const scoped_refptr<base::SingleThreadTaskRunner>& main_thread,
+      webrtc::AudioTrackInterface* webrtc_track);
+
+  void Unregister();
+
+ protected:
+  ~RemoteAudioTrackAdapter() override;
+
+ private:
+  void InitializeWebAudioTrack();
+
+  // webrtc::ObserverInterface implementation.
+  void OnChanged() override;
+
+  void OnChangedOnMainThread(
+      webrtc::MediaStreamTrackInterface::TrackState state);
+
+#if DCHECK_IS_ON()
+  bool unregistered_;
+#endif
+
+  webrtc::MediaStreamTrackInterface::TrackState state_;
+
+  DISALLOW_COPY_AND_ASSIGN(RemoteAudioTrackAdapter);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_MEDIA_REMOTE_MEDIA_TRACK_ADAPTER_H_