Apple ported KHTML to Mac OS, calling it Webkit. It was released as part of the initial Safari release in 2003. They had a breakup with KHTML a few years later and open sourced Webkit separately. Webkit then became the basis for Chrome when it was launched by Google, until they forked in turn and made Blink.
A browser has many other parts than rendering engine. So it is not fair to say Chrome is derived from webkit or safari. You can say chrome rendering engine was initially based on webkit which was based on khtml. And today that shared parts are quite small in the general picture.
