Comment by norberg

We have stopped pushing the affected version of Keystone, so if your computer has not been broken yet, it won't be.

If it has been broken but not rebooted:

  sudo rm -rf /Library/Google/GoogleSoftwareUpdate/GoogleSoftwareUpdate.bundle
  sudo ln /private/var /var

should fix it. That deletes Keystone and fixes the symlink. If it has been rebooted, these commands at a recovery console should repair the computer.

Chrome will subsequently ask for admin credentials to reinstall the updater next time you run it. This will not re-break the computer; the version of Keystone bundled with Chrome is older, and we have stopped serving the version affected by this issue.