LocationManagerService: Add NullPointerException to avoid change in behavior.

After fixing a null pointer check we were no longer throwing NullPointerExceptions
which caused a CTS test to fail.

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

services/java/com/android/server/LocationManagerService.java

@@ -1100,6 +1100,11 @@ public class LocationManagerService extends ILocationManager.Stub implements Run
     }
 
     public boolean sendExtraCommand(String provider, String command, Bundle extras) {
+        if (provider == null) {
+            // throw NullPointerException to remain compatible with previous implementation
+            throw new NullPointerException();
+        }
+
         // first check for permission to the provider
         checkPermissionsSafe(provider);
         // and check for ACCESS_LOCATION_EXTRA_COMMANDS