Create //webrtc/api:libjingle_peerconnection_api + refactorings.

webrtc/api/mediastreamobserver.h

-/*
- *  Copyright 2015 The WebRTC project authors. All Rights Reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-#ifndef WEBRTC_API_MEDIASTREAMOBSERVER_H_
-#define WEBRTC_API_MEDIASTREAMOBSERVER_H_
-
-#include "webrtc/api/mediastreaminterface.h"
-#include "webrtc/base/scoped_ref_ptr.h"
-#include "webrtc/base/sigslot.h"
-
-namespace webrtc {
-
-// Helper class which will listen for changes to a stream and emit the
-// corresponding signals.
-class MediaStreamObserver : public ObserverInterface {
- public:
-  explicit MediaStreamObserver(MediaStreamInterface* stream);
-  ~MediaStreamObserver();
-
-  const MediaStreamInterface* stream() const { return stream_; }
-
-  void OnChanged() override;
-
-  sigslot::signal2<AudioTrackInterface*, MediaStreamInterface*>
-      SignalAudioTrackAdded;
-  sigslot::signal2<AudioTrackInterface*, MediaStreamInterface*>
-      SignalAudioTrackRemoved;
-  sigslot::signal2<VideoTrackInterface*, MediaStreamInterface*>
-      SignalVideoTrackAdded;
-  sigslot::signal2<VideoTrackInterface*, MediaStreamInterface*>
-      SignalVideoTrackRemoved;
-
- private:
-  rtc::scoped_refptr<MediaStreamInterface> stream_;
-  AudioTrackVector cached_audio_tracks_;
-  VideoTrackVector cached_video_tracks_;
-};
-
-}  // namespace webrtc
-
-#endif  // WEBRTC_API_MEDIASTREAMOBSERVER_H_