Although some ARM-driven Chromebooks do not need patching, there are also a few Chrome OS-powered notebooks that will not get any sort of protection from Meltdown and Spectre, including the Acer C7 and the Samsung Chromebook 5.
https://www.notebookcheck.net/Meltdown-and-Spectre-patches-not-coming-to-older-Chromebooks.277862.0.html