Remove non-exist class MediaStream. (#308)

packager/media/demuxer/demuxer.h

@@ -26,7 +26,6 @@ class Decryptor;
 class KeySource;
 class MediaParser;
 class MediaSample;
-class MediaStream;
 class StreamInfo;
 
 /// Demuxer is responsible for extracting elementary stream samples from a

packager/media/formats/mp4/segmenter.h

@@ -50,7 +50,7 @@ class Segmenter {
   /// Initialize the segmenter.
   /// Calling other public methods of this class without this method returning
   /// Status::OK results in an undefined behavior.
-  /// @param streams contains the vector of MediaStreams to be segmented.
+  /// @param streams contains the vector of StreamInfos for initialization.
   /// @param muxer_listener receives muxer events. Can be NULL.
   /// @param progress_listener receives progress updates. Can be NULL.
   /// @return OK on success, an error status otherwise.