The Google Domain Verification plugin enables October to respond to Google domain verification requests through the "Uploaded file" verification method.
Manage the Google Domain Verification Codes for your website by going to Settings -> Misc -> Google Domain Verification. Google provides you a HTML file named something like "google1d4b46d16655aed1.html". Click on the "Add new code" button and simply paste the file name (without the .html part) into the "Code" field. You can also optionally provide a description of the code being added (i.e. "Dave's verification code") to identify it. Add as many verification codes as required, there are no restrictions on the number of codes you can add.
The Google Domain Verification provides a permission (Manage Verification Codes) that can be applied to specific users to control who has access to the domain verification codes that are allowed on the site.