That type of rifling has nothing to do with the chrome plating, which was standard on the Type 99 right up to the very late rifles.
The Japanese used Metford rifling, something they got from the British, who were using it in the Lee-Metford (Lee rifle, Metford rifling - Lee Enfield is Lee rifle, Enfield type rifling) at the time the Japanese were designing the Arisaka rifles and they never saw any reason to change it.
Metford riflling was designed to minimize cupro-nickel fouling. Lands are rounded off and looking down the barrel the rifling appears as shadows rather than the sharp appearance of conventional rifling.
If one is a bit unscrupulous, and one wants to buy a Japanese rifle, one can get a lower price by telling the owner that the rifling is all worn out.