If you were waiting for Project Crostini to move past the Dev Channel, you’re going to be waiting a little longer. Google has decided to hold the feature, which lets you run full Linux apps in a container, to Chrome 69 for both the Beta and Stable Channels. We want to release to dev/canary for version 67 and 68 and to release to all chanels[sic] since version 69.
Link: Project Crostini for Linux apps on Chromebooks pushed back to Chrome 69 for Beta and Stable
via http://www.aboutchromebooks.com