Remove RefBase from the extractor API

- Add MetaDataBase base class that MetaData derives from, but which
  does not derive from RefBase.
- MediaBuffer::meta_data() now returns a MetaDataBase& rather than an
  sp<MetaData>
- Rename MediaSourceBase to MediaTrack.
- MediaSource no longer derives from MediaSourceBase (or MediaTrack)
- MediaTrack::getFormat(), MediaExtractor::getTrackMetaData() and
  MediaExtractor::getMetaData() all take a MetaDataBase& parameter that
  they fill out, rather than returning a MetaData directly (the
  corresponding methods on MediaSource and RemoteMediaExtractor continue
  to return MetaData)

Bug: 67908544
Test: CTS MediaPlayerTest, DecoderTest, EncodeDecodeTest, manually record video

Change-Id: Ib531ab309061290be33d40d6100c9a8127e22083
diff --git a/media/libmediaplayerservice/nuplayer/NuPlayerDrm.h b/media/libmediaplayerservice/nuplayer/NuPlayerDrm.h
index 6b8a2d9..50f69ff 100644
--- a/media/libmediaplayerservice/nuplayer/NuPlayerDrm.h
+++ b/media/libmediaplayerservice/nuplayer/NuPlayerDrm.h
@@ -109,7 +109,7 @@
                 size_t *clearbytes,
                 size_t *encryptedbytes);
 
-        static CryptoInfo *getSampleCryptoInfo(sp<MetaData> meta);
+        static CryptoInfo *getSampleCryptoInfo(MetaDataBase &meta);
 
     };  // NuPlayerDrm