MSE: Add StreamParser buffer remuxing utility and tests

media/formats/webm/webm_cluster_parser.cc

Index: media/formats/webm/webm_cluster_parser.cc
diff --git a/media/formats/webm/webm_cluster_parser.cc b/media/formats/webm/webm_cluster_parser.cc
index 67e6d82576c9755e1b4a995da25645f8f8e7cc37..9a921f37e7bb523df6d6f548fec75dcac380d28a 100644
--- a/media/formats/webm/webm_cluster_parser.cc
+++ b/media/formats/webm/webm_cluster_parser.cc
@@ -292,7 +292,7 @@ bool WebMClusterParser::OnBlock(bool is_simple_block, int track_num,
   }
 
   Track* track = NULL;
-  bool is_text = false;
+  StreamParserBuffer::Type buffer_type = StreamParserBuffer::kAudio;
   std::string encryption_key_id;
   if (track_num == audio_.track_num()) {
     track = &audio_;
@@ -300,6 +300,7 @@ bool WebMClusterParser::OnBlock(bool is_simple_block, int track_num,
   } else if (track_num == video_.track_num()) {
     track = &video_;
     encryption_key_id = video_encryption_key_id_;
+    buffer_type = StreamParserBuffer::kVideo;
   } else if (ignored_tracks_.find(track_num) != ignored_tracks_.end()) {
     return true;
   } else if (Track* const text_track = FindTextTrack(track_num)) {
@@ -308,7 +309,7 @@ bool WebMClusterParser::OnBlock(bool is_simple_block, int track_num,
     if (block_duration < 0)  // not specified
       return false;
     track = text_track;
-    is_text = true;
+    buffer_type = StreamParserBuffer::kText;
   } else {
     MEDIA_LOG(log_cb_) << "Unexpected track number " << track_num;
     return false;
@@ -320,7 +321,7 @@ bool WebMClusterParser::OnBlock(bool is_simple_block, int track_num,
       (cluster_timecode_ + timecode) * timecode_multiplier_);
 
   scoped_refptr<StreamParserBuffer> buffer;
-  if (!is_text) {
+  if (buffer_type != StreamParserBuffer::kText) {
     // The first bit of the flags is set when a SimpleBlock contains only
     // keyframes. If this is a Block, then inspection of the payload is
     // necessary to determine whether it contains a keyframe or not.
@@ -345,7 +346,8 @@ bool WebMClusterParser::OnBlock(bool is_simple_block, int track_num,
     buffer = StreamParserBuffer::CopyFrom(
         data + data_offset, size - data_offset,
         additional, additional_size,
-        is_keyframe);
+        is_keyframe, buffer_type);
+    buffer->set_text_track_number(track_num);
 
     if (decrypt_config)
       buffer->set_decrypt_config(decrypt_config.Pass());
@@ -363,7 +365,8 @@ bool WebMClusterParser::OnBlock(bool is_simple_block, int track_num,
         content.length(),
         &side_data[0],
         side_data.size(),
-        true);
+        true, StreamParserBuffer::kText);
+    buffer->set_text_track_number(track_num);
   }
 
   buffer->set_timestamp(timestamp);