Google Drive Blog I discovered that this feature has been out since Wednesday.
Other Google Drive for iOS and Android updates that you might missed this week include updates to Sheets that allow you to hide rows and columns. Google Sheets itself (the web version) has new options for locking a sheet or range and sharing it with only some of the collaborators on a file.
Applications for Education
If you're using Sheets with students, the option to lock them into only part of spreadsheet could be helpful in focusing them on a specific subset of data within a much larger data set.