Fix some metadata retriever issues:
1. mRetriever was initialized twice: one in the constructor and the other in the setDataSource
2. cached the mode so that setMode can still be called before setDataSource.
   mRetriever won't be initialized until data source is set; thus we have to do this
diff --git a/media/libmediaplayerservice/MetadataRetrieverClient.h b/media/libmediaplayerservice/MetadataRetrieverClient.h
index 88d50bf..8cb8ad1 100644
--- a/media/libmediaplayerservice/MetadataRetrieverClient.h
+++ b/media/libmediaplayerservice/MetadataRetrieverClient.h
@@ -60,6 +60,7 @@
     mutable Mutex                          mLock;
     sp<MediaMetadataRetrieverBase>         mRetriever;
     pid_t                                  mPid;
+    int                                    mMode;
 
     // Keep the shared memory copy of album art and capture frame (for thumbnail)
     sp<MemoryDealer>                       mAlbumArtDealer;