GNOME 3.18 added the ability to access Google Drive directly from 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 for the most part however, because Unity doesn’t use GNOME Control Center (also known as GNOME System Settings or just Settings) and GNOME Online Accounts and instead, it ships with a fork (unity-control-center), it doesn’t include this feature by default.
Even so, you can use the GNOME 3.18 Google Drive integration in Unity as well as other desktop environments. Read on!