Los "chinos" se refieren originalmente al material usado en uniformes militares:
"Chino cloth is a twill fabric, originally made of 100% cotton. The most common items made from it, trousers, are widely called chinos. Today it is also found in cotton-synthetic blends. Developed in the mid-19th century for British and French military uniforms, it has since migrated into civilian wear. Trousers of such a fabric gained popularity in the U.S. when Spanish–American War veterans returned from the Philippines with their twill military trousers.
As the cloth itself was originally made in China, the trousers were known in Spanish as pantalones chinos (Chinese pants), which became shortened to simply "chinos" in English."
https://en.wikipedia.org/wiki/Chino_cloth
En cuanto a la raya, en su origen podía estar presente en los pantalones de los oficiales:
https://web.archive.org/web/20131012...-of-the-chino/