Add support for "album artist" tag.
diff --git a/include/media/mediametadataretriever.h b/include/media/mediametadataretriever.h
index 022b849..9b12410 100644
--- a/include/media/mediametadataretriever.h
+++ b/include/media/mediametadataretriever.h
@@ -55,6 +55,7 @@
     METADATA_KEY_WRITER          = 21,
     METADATA_KEY_MIMETYPE        = 22,
     METADATA_KEY_DISC_NUMBER     = 23,
+    METADATA_KEY_ALBUMARTIST     = 24,
     // Add more here...
 };