Google is changing the FileSystem API so that it can be used in incognito mode without the risks to privacy. Chrome Chrome currently allows sites to create a virtual file system that lives within the sandbox of the browser. This allows sites that utilize large assets to download these assets to a virtual system so that they do not have to download them each time they are needed. Google will require the site to state in advance how large the requested file system should be to avoid using all of the available memory.
Source: https://www.bleepingcomputer.com/news/google/google-fixing-chrome-api-to-prevent-incognito-mode-detection/