The third Chrome 68-based build in as many weeks has landed in the Chrome OS Beta Channel. Build 68.0.3440.40 (Platform version: 10718.34.0) is the updated version for those keeping score at home and should be available to the majority of devices that are in the channel.
As always, for those who have a device registered in the Beta Channel, you can just type chrome://help in the browser ominbar which will bring you to the build information on your Chromebook. There you will see a Check for Update button which will download the latest build to your device.
As you would expect with this being a beta build, the bulk of the updates in this new build are bug and security fixes. There are also a number of policy changes in this update according to the release notes, most of which appear to be aimed at security and stability. Of course the biggest news right is the new wallpaper picker and non-secure websites will be clearly noted in the omnibar of the browser across all platforms.
We still are several weeks away from a release of Chrome 68 for Chrome OS. The release of Chrome 68 itself is expected to happen on July 24th while Chrome OS will get updated on or around July 31st. You can expect to see a few more beta builds in the meantime as testers and Google smooth things out for the Stable release.
Remember that you can always get information on all the Chrome OS channels and the current builds for each of them on the Builds page here on the site.