The box will automatically disappear and the install will begin after 5 minutes. IF you click OK, the install will begin immediately. If you are logged into the computer, the "postpone" option will appear. By clicking the postpone option, it will "cancel" the update until the next Group Policy Update (GPU). GPU happens during every login and every subsequent 30 minutes.
We apologize for the short notice, but Chrome only supports one version back of their current browser and we want to make sure ALL testing is not impacted by this change. Thanks for your understanding.