Generate and assign media track ids in demuxers.

media/filters/media_source_state.cc

Index: media/filters/media_source_state.cc
diff --git a/media/filters/media_source_state.cc b/media/filters/media_source_state.cc
index 6a1d95f6190f3369ab66db489c948abcafade5d1..b3cf09efcad17bc79f12e3df5634e25c70ddaf26 100644
--- a/media/filters/media_source_state.cc
+++ b/media/filters/media_source_state.cc
@@ -151,8 +151,8 @@ void MediaSourceState::SetGroupStartTimestampIfInSequenceMode(
 void MediaSourceState::SetTracksWatcher(
     const Demuxer::MediaTracksUpdatedCB& tracks_updated_cb) {
   DCHECK(init_segment_received_cb_.is_null());
+  DCHECK(!tracks_updated_cb.is_null());
   init_segment_received_cb_ = tracks_updated_cb;
-  DCHECK(!init_segment_received_cb_.is_null());
 }
 
 bool MediaSourceState::Append(const uint8_t* data,
@@ -481,9 +481,22 @@ bool MediaSourceState::OnNewConfigs(
   DCHECK_GE(state_, PENDING_PARSER_CONFIG);
   DCHECK(tracks.get());
 
-  media_tracks_ = std::move(tracks);
-  const AudioDecoderConfig& audio_config = media_tracks_->getFirstAudioConfig();
-  const VideoDecoderConfig& video_config = media_tracks_->getFirstVideoConfig();
+  MediaTrack* audio_track = nullptr;
+  MediaTrack* video_track = nullptr;
+  AudioDecoderConfig audio_config;
+  VideoDecoderConfig video_config;
+  for (const auto& track : tracks->tracks()) {

[wolenetz, 2016/06/13 19:51:37]

This CL drops all usage of MediaTracks::getFirst{Audio,Video}Config(). Please
remove those methods, too in this CL.

[servolk, 2016/06/13 22:00:16]

No, there's still a couple of places where we use getFirstA/VConfig in unit
tests. I'll update and land this removal of getFirstA/VConfig as a separate CL
after this one lands:
https://codereview.chromium.org/1833053005/

[wolenetz, 2016/06/13 23:23:57]

Acknowledged. My apologies :)

+    const auto& track_id = track->bytestream_track_id();
+    if (!audio_track && track->type() == MediaTrack::Audio &&
+        tracks->getAudioConfig(track_id).IsValidConfig()) {

[wolenetz, 2016/06/13 19:51:37]

I'm not sure we should now allow multiple invalid configs to pass here without
emitting decode error. Why are we filtering on IsValidConfig() here? (and
similarly, for video case in else clause)?

[servolk, 2016/06/13 22:00:16]

Yeah, good point, I've updated this to reject multiple a/v tracks with logging
into MEDIA_LOG. Also, now that media track code is getting stable I believe each
track should have a valid a/v config associated with it, so converted the
IsValidConfig to DCHECKs.

+      audio_config = tracks->getAudioConfig(track_id);
+      audio_track = track.get();
+    } else if (!video_track && track->type() == MediaTrack::Video &&
+               tracks->getVideoConfig(track_id).IsValidConfig()) {
+      video_config = tracks->getVideoConfig(track_id);
+      video_track = track.get();
+    }
+  }
 
   DVLOG(1) << "OnNewConfigs(" << allow_audio << ", " << allow_video << ", "
            << audio_config.IsValidConfig() << ", "
@@ -652,12 +665,21 @@ bool MediaSourceState::OnNewConfigs(
 
   frame_processor_->SetAllTrackBuffersNeedRandomAccessPoint();
 
+  if (audio_track) {
+    DCHECK(audio_);
+    audio_track->set_id(audio_->media_track_id());
+  }
+  if (video_track) {
+    DCHECK(video_);
+    video_track->set_id(video_->media_track_id());
+  }
+
   DVLOG(1) << "OnNewConfigs() : " << (success ? "success" : "failed");
   if (success) {
     if (state_ == PENDING_PARSER_CONFIG)
       state_ = PENDING_PARSER_INIT;
     DCHECK(!init_segment_received_cb_.is_null());
-    init_segment_received_cb_.Run(std::move(media_tracks_));
+    init_segment_received_cb_.Run(std::move(tracks));
   }
 
   return success;