Use immediately invoked lambda for tracking_to_local. (#848)
Use immediately invoked lambda for tracking_to_local. (#848)

Restores const-correctness that we dropped when introducing the 
`publish_frame_projected_to_2d` param without using a ternary operator.
cartographer-project/cartographer_ros,damonkohler/cartographer_ros,googlecartographer/cartographer_ros,damonkohler/cartographer_ros,wohe/cartographer_ros,damonkohler/cartographer_ros,cartographer-project/cartographer_ros,cartographer-project/cartographer_ros,googlecartographer/cartographer_ros,googlecartographer/cartographer_ros,wohe/cartographer_ros,wohe/cartographer_ros