gps: Unhide GpsStatus.NmeaListener interface for receiving NMEA sentences

Signed-off-by: Mike Lockwood <lockwood@android.com>

location/java/android/location/GpsStatus.java

@@ -116,9 +116,12 @@ public final class GpsStatus {
     }
 
     /**
-     * Used for receiving NMEA data from the GPS.
-     *
-     * {@hide}
+     * Used for receiving NMEA sentences from the GPS.
+     * NMEA 0183 is a standard for communicating with marine electronic devices
+     * and is a common method for receiving data from a GPS, typically over a serial port.
+     * See <a href="http://en.wikipedia.org/wiki/NMEA_0183">NMEA 0183</a> for more details.
+     * You can implement this interface and call {@link LocationManager#addNmeaListener}
+     * to receive NMEA data from the GPS engine.
      */
     public interface NmeaListener {
         void onNmeaReceived(long timestamp, String nmea);