Adding VP8 Alpha support in Media Source

media/webm/webm_tracks_parser.cc

Index: media/webm/webm_tracks_parser.cc
diff --git a/media/webm/webm_tracks_parser.cc b/media/webm/webm_tracks_parser.cc
index 4cf6f4a1dffdd34e819f9f7b4f0d465d978a5a2f..414b4c40d0b4f4342910baa55a669814128998b9 100644
--- a/media/webm/webm_tracks_parser.cc
+++ b/media/webm/webm_tracks_parser.cc
@@ -31,6 +31,7 @@ static TextKind CodecIdToTextKind(const std::string& codec_id) {
 WebMTracksParser::WebMTracksParser(const LogCB& log_cb)
     : track_type_(-1),
       track_num_(-1),
+      max_block_additional_id_(-1),
       audio_track_num_(-1),
       video_track_num_(-1),
       log_cb_(log_cb),
@@ -75,6 +76,7 @@ WebMParserClient* WebMTracksParser::OnListStart(int id) {
     track_num_ = -1;
     track_name_.clear();
     track_language_.clear();
+    max_block_additional_id_ = -1;
     codec_id_ = "";
     codec_private_.clear();
     audio_client_.Reset();
@@ -198,6 +200,7 @@ bool WebMTracksParser::OnListEnd(int id) {
     track_num_ = -1;
     track_name_.clear();
     track_language_.clear();
+    max_block_additional_id_ = -1;
     codec_id_ = "";
     codec_private_.clear();
     track_content_encodings_client_.reset();
@@ -220,6 +223,9 @@ bool WebMTracksParser::OnUInt(int id, int64 val) {
     case kWebMIdTrackType:
       dst = &track_type_;
       break;
+    case kWebMIdMaxBlockAdditionId:
+      dst = &max_block_additional_id_;
+      break;
     default:
       return true;
   }