Implemented the metadata changed notification filters.

IMediaPlayer:
new setMetadataFilter method so set a filter (2 lists of allowed and blocked metadata type)
serialized in a Parcel.

MediaPlayer.java/android_media_MediaPlayer.cpp/mediaplayer.cpp
new setMetadataFilter that passes the filter down to the MediaPlayerService's binder interface.

MediaPlayerService.cpp
The Client inner class holds the allowed and blocked metadata types.
These are in 2 vectors that get populated in the setMetadataFilter.

A new shourldDropMetadata method returns true if a type of metadata should be dropped according
to the filters.

The notify method in run the metadata update notifications thru the filter and possibly drop them.
diff --git a/include/media/mediaplayer.h b/include/media/mediaplayer.h
index dd8ea19..8326a21 100644
--- a/include/media/mediaplayer.h
+++ b/include/media/mediaplayer.h
@@ -97,6 +97,8 @@
     MEDIA_INFO_BAD_INTERLEAVING = 800,
     // The media is not seekable (e.g live stream).
     MEDIA_INFO_NOT_SEEKABLE = 801,
+    // New media metadata is available.
+    MEDIA_INFO_METADATA_UPDATE = 802,
 };
 
 
@@ -152,6 +154,7 @@
     static  sp<IMemory>     decode(const char* url, uint32_t *pSampleRate, int* pNumChannels, int* pFormat);
     static  sp<IMemory>     decode(int fd, int64_t offset, int64_t length, uint32_t *pSampleRate, int* pNumChannels, int* pFormat);
             status_t        invoke(const Parcel& request, Parcel *reply);
+            status_t        setMetadataFilter(const Parcel& filter);
 private:
             void            clear_l();
             status_t        seekTo_l(int msec);