GNOME 3.18 has added access to Google Drive directly from your files (Nautilus). To use this feature, all you have to do is add your Google Account to GNOME Online Accounts and enable "Files".
Ubuntu 16.04 Xenial Xerus already includes GNOME 3.18, but Unity does not use the GNOME Control Center. So, to be able to integrate Google Drive into Unity, as well as other desktop environments, you need to install the GNOME Control Center. It works for all derivatives of Ubuntu 16.04 Xenial Xerus (Kubuntu, Xubuntu, etc.).
Before proceeding, please note that Google Drive is added via GVfs, so any changes you make to the Google Drive folder on your computer are mirrored in your Google Drive account (and vice versa), but you will not have access to other features available to all its official clients Google Drive on Windows and Mac, with options to share files, etc.
Let's see how it works:
Installing GNOME Control Center and GNOME Online Accounts:
sudo apt-get install gnome-online-accounts
Then search for "Settings" in Dash, click on the icon and GNOME System Settings will run.
GNOME System Settings (GNOME Control Center) appears as "Settings" in the Dash. "System Settings" is for Unity.
You can also run GNOME System Settings from the terminal:
or to directly open the GNOME Online Accounts window, run the command:
You can now add your account and activate "Files".