How can I have Google Chrome Canary for Ubuntu?
As stated in the site you linked, Canary builds are not available for Linux.
The only release channels available for Linux are: Stable, Beta and Dev.
The reason for that is explained here:
Thanks for your interesting in testing out the latest and greatest builds of Chrome. There are logistical challenges that make creating/ deploying Linux bundles prohibitively expensive to do on a daily basis, which effectively makes a Linux Canary fairly unlikely for the foreseeable future. I'd encourage the community to use the PPA builds, those are fundamentally the same as what we would build save for a couple of plugins (PDF, Flash, FFMpeg).
Anthony Laforge Technical Program Manager Mountain View, CA
As the date of today 2019-02-07, this binary is Version 74.0.3697.0 (Developer Build) (64-bit)
Chromium Dev seria como Canary