Hookup the MediaStream glue for Adding and Removing tracks to an existing MediaStream.

content/renderer/media/media_stream_center.cc

 // 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.
 
 #include "content/renderer/media/media_stream_center.h"
 
 #include <string>
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 14 matching lines @@
 
 namespace content {
 
 static webrtc::MediaStreamInterface* GetNativeMediaStream(
     const WebKit::WebMediaStream& stream) {
   MediaStreamExtraData* extra_data =
       static_cast<MediaStreamExtraData*>(stream.extraData());
   return extra_data->stream();
 }
 
-
 static webrtc::MediaStreamTrackInterface* GetNativeMediaStreamTrack(
       const WebKit::WebMediaStream& stream,
       const WebKit::WebMediaStreamTrack& component) {
   std::string track_id = UTF16ToUTF8(component.id());
   webrtc::MediaStreamInterface* native_stream = GetNativeMediaStream(stream);
   if (native_stream) {
     if (component.source().type() == WebKit::WebMediaStreamSource::TypeAudio) {
       return native_stream->FindAudioTrack(track_id);
     }
     if (component.source().type() == WebKit::WebMediaStreamSource::TypeVideo) {
@@ skipping 46 matching lines @@
   extra_data->OnLocalStreamStop();
 }
 
 void MediaStreamCenter::didCreateMediaStream(
     WebKit::WebMediaStream& stream) {
   if (!rtc_factory_)
     return;
   rtc_factory_->CreateNativeLocalMediaStream(&stream);
 }
 
+bool MediaStreamCenter::didAddMediaStreamTrack(

[henrika (OOO until Aug 14), 2013/04/09 16:53:43]

Why do we return bool here but void for didCreateMediaStream?
What happens in the false case?

[perkj_chrome, 2013/04/10 19:58:00]

Good question- this is WebKit magic. Normally an exception is created in JS if
we return false. void functions can't throw an exception.

+    const WebKit::WebMediaStream& stream,
+    const WebKit::WebMediaStreamTrack& track) {
+  if (!rtc_factory_) {

[tommi (sloooow) - chröme, 2013/04/09 13:28:49]

no {}

[perkj_chrome, 2013/04/10 19:58:00]

Done.

+    return false;
+  }
+  return rtc_factory_->AddNativeLocalMediaTrack(stream, track);

[henrika (OOO until Aug 14), 2013/04/09 16:53:43]

Why is the rtc_factory used for didAdd but bot for didRemove? I just feels like
an odd design to me (feels asymmetric that's all).

[perkj_chrome, 2013/04/10 19:58:00]

make sence. Moved Removed.

+}
+
+bool MediaStreamCenter::didRemoveMediaStreamTrack(
+    const WebKit::WebMediaStream& stream,
+    const WebKit::WebMediaStreamTrack& track) {
+  webrtc::MediaStreamInterface* native_stream =  GetNativeMediaStream(stream);
+  WebKit::WebMediaStreamSource::Type type = track.source().type();
+  std::string track_id = UTF16ToUTF8(track.id());
+  if (type == WebKit::WebMediaStreamSource::TypeAudio) {

[tommi (sloooow) - chröme, 2013/04/09 13:28:49]

This looks a bit hard to read and spot the three return statements.  What about
doing this instead (I'm assuming that since you have a NOTREACHED(), the type
will always be either audio or video):

webrtc::MediaStreamInterface* native_stream =  GetNativeMediaStream(stream);
WebKit::WebMediaStreamSource::Type type = track.source().type();
DCHECK(type == WebKit::WebMediaStreamSource::TypeAudio ||
       type == WebKit::WebMediaStreamSource::TypeVideo);

return type == WebKit::WebMediaStreamSource::TypeAudio ?
    native_stream->RemoveTrack(native_stream->FindAudioTrack(track_id)) :
    native_stream->RemoveTrack(native_stream->FindVideoTrack(track_id))

[perkj_chrome, 2013/04/10 19:58:00]

Done.

+    webrtc::AudioTrackInterface* audio_track =
+        native_stream->FindAudioTrack(track_id);
+    return native_stream->RemoveTrack(audio_track);
+  } else if (type == WebKit::WebMediaStreamSource::TypeVideo) {
+    webrtc::VideoTrackInterface* video_track =
+        native_stream->FindVideoTrack(track_id);
+    return native_stream->RemoveTrack(video_track);
+  }
+  NOTREACHED();
+  return false;
+}
+
 }  // namespace content