TBA: 'Clear private data' option does not clear browsing history
Almost all visited URLs are saved in
/data/data/org.torproject.torbrowser_alpha/files/mozilla/profile.default/browser.db-wal. Clearing private data from the settings or pressing the 'Quit' button does not delete that file. So basically all browsing history is still stored after clearing private data. After clearing private data in the settings, it does say that some private data could not be deleted but if 'Site settings' is unchecked, it doesn't say that anymore. So normally we'd think that only site settings are not cleared.