MediaRecorder: make MediaRecorderHandler a MediaStreamObserver

content/renderer/media/media_recorder_handler.cc

 // Copyright 2015 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.
 
 #include "content/renderer/media/media_recorder_handler.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/strings/string_tokenizer.h"
@@ skipping 75 matching lines @@
   // Save histogram data so we can see how much MediaStream Recorder is used.
   // The histogram counts the number of calls to the JS API.
   UpdateWebRTCMethodCount(WEBKIT_MEDIA_STREAM_RECORDER);
 
   if (!canSupportMimeType(type, codecs)) {
     DLOG(ERROR) << "Can't support " << type.utf8()
                 << ";codecs=" << codecs.utf8();
     return false;
   }
   use_vp9_ = base::ToLowerASCII(codecs.utf8()).find("vp9") != std::string::npos;
-  media_stream_ = media_stream;
   DCHECK(client);
   client_ = client;
 
+  media_stream_ = media_stream;
+  DCHECK(MediaStream::GetMediaStream(media_stream));

[perkj_chrome, 2016/01/07 09:18:00]

no need for this check. The same will happen on the line below if
MediaStream::GetMediaStream return null.

[mcasas, 2016/01/08 00:14:12]

Done.

+  MediaStream::GetMediaStream(media_stream)->AddObserver(this);
+
   return true;
 }
 
 bool MediaRecorderHandler::start() {
   DCHECK(main_render_thread_checker_.CalledOnValidThread());
   DCHECK(!recording_);
   return start(0);
 }
 
 bool MediaRecorderHandler::start(int timeslice) {
@@ skipping 85 matching lines @@
 }
 
 void MediaRecorderHandler::resume() {
   DCHECK(main_render_thread_checker_.CalledOnValidThread());
   DCHECK(!recording_);
   recording_ = true;
   for (const auto& video_recorder : video_recorders_)
     video_recorder->Resume();
 }
 
+void MediaRecorderHandler::TrackAdded(const blink::WebMediaStreamTrack& track) {
+  WriteData(base::StringPiece(""));

[perkj_chrome, 2016/01/07 09:18:00]

Why is WriteData(base::StringPiece necessary here but not in the normal stop
condition? If it is required always, move to stop() ? 

[mcasas, 2016/01/08 00:14:12]

Actually both writeData() and stop() are not needed
since client->onError() (new name of fail...() ) will do
all necessary steps to stop the recording. Both 
removed.

+  stop();
+  client_->failIllegalStreamModification("Track added");
+}
+
+void MediaRecorderHandler::TrackRemoved(
+    const blink::WebMediaStreamTrack& track) {
+  WriteData(base::StringPiece(""));
+  stop();
+  client_->failIllegalStreamModification("Track removed");
+}
+
 void MediaRecorderHandler::OnEncodedVideo(
     const scoped_refptr<media::VideoFrame>& video_frame,
     scoped_ptr<std::string> encoded_data,
     TimeTicks timestamp,
     bool is_key_frame) {
   DCHECK(main_render_thread_checker_.CalledOnValidThread());
   if (!webm_muxer_)
     return;
   webm_muxer_->OnEncodedVideo(video_frame, encoded_data.Pass(), timestamp,
                               is_key_frame);
@@ skipping 38 matching lines @@
     recorder->OnData(audio_bus, timestamp);
 }
 
 void MediaRecorderHandler::SetAudioFormatForTesting(
     const media::AudioParameters& params) {
   for (auto* recorder : audio_recorders_)
     recorder->OnSetFormat(params);
 }
 
 }  // namespace content