Where is my chrome extension 'OneTab' data?

Your OneTab data can be found at C:/Users/<Username>/AppData/Local/Google/Chrome/User Data/Default/Local Storage/leveldb. Just replace <Username> with your user's username.

I also created a Python script to automatically back up your OneTab data.

https://github.com/itsjoshthedeveloper/backupOneTab

More information found in the link above.

This seems to be the latest place where the files are located:

C:\Users\yourname\AppData\Local\Google\Chrome\User Data\Default\Extensions\chphlpgkkbolifaimnlloiipkdnihall