MediaPlayer2: initial code for playlist support

Test: MediaPlayer2 plays
Bug: 63934228
Change-Id: If63c97e225759108a30bb58ab0870569e0878ade
diff --git a/media/libmediaplayer2/include/mediaplayer2/MediaPlayer2Engine.h b/media/libmediaplayer2/include/mediaplayer2/MediaPlayer2Engine.h
index 2d1a24b..749d83c 100644
--- a/media/libmediaplayer2/include/mediaplayer2/MediaPlayer2Engine.h
+++ b/media/libmediaplayer2/include/mediaplayer2/MediaPlayer2Engine.h
@@ -48,6 +48,8 @@
     virtual void            disconnect() = 0;
 
     virtual status_t        setDataSource(const sp<DataSourceDesc>& source) = 0;
+    virtual status_t        prepareNextDataSource(const sp<DataSourceDesc>& source) = 0;
+    virtual status_t        playNextDataSource(int64_t srcId) = 0;
     virtual status_t        setVideoSurfaceTexture(const sp<ANativeWindowWrapper>& nww) = 0;
     virtual status_t        getBufferingSettings(
                                     BufferingSettings* buffering /* nonnull */) = 0;