Basic plumbing to retrieve metadata from the native player.

IMediaPlayer.h
Added a getMetadata method that mirrors the on in MediaPlayer.java.

MediaPlayer.java
Added a native method to get the metadata from the native player.
Parse the parcel into a Metadata object.

Metadata.java
Added a stub to parse the Parcel returned by the native player into
a set of metadata.

android_media_MediaPlayer.cpp
JNI call to forward the getMetadata call.

MediaPlayerService.cpp
MediaPlayerService::Client implements the new getMetadata method added in IMediaPlayer.h
diff --git a/media/libmediaplayerservice/MediaPlayerService.h b/media/libmediaplayerservice/MediaPlayerService.h
index b915e86..7920559 100644
--- a/media/libmediaplayerservice/MediaPlayerService.h
+++ b/media/libmediaplayerservice/MediaPlayerService.h
@@ -191,6 +191,7 @@
         virtual status_t        setVolume(float leftVolume, float rightVolume);
         virtual status_t        invoke(const Parcel& request, Parcel *reply);
         virtual status_t        setMetadataFilter(const Parcel& filter);
+        virtual status_t        getMetadata(bool update_only, bool apply_filter, Parcel *metadata);
 
         sp<MediaPlayerBase>     createPlayer(player_type playerType);
                 status_t        setDataSource(const char *url);