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.cpp b/media/libmediaplayerservice/MediaPlayerService.cpp
index 3adbfac..04aab81 100644
--- a/media/libmediaplayerservice/MediaPlayerService.cpp
+++ b/media/libmediaplayerservice/MediaPlayerService.cpp
@@ -846,6 +846,16 @@
     return status;
 }
 
+status_t MediaPlayerService::Client::getMetadata(bool update_only, bool apply_filter, Parcel *metadata)
+{
+    status_t status;
+    metadata->writeInt32(-1);  // Placeholder for the return code
+
+    // FIXME: Implement, query the native player and do the optional filtering, etc...
+    status = OK;
+    return status;
+}
+
 status_t MediaPlayerService::Client::prepareAsync()
 {
     LOGV("[%d] prepareAsync", mConnId);