For example, the Chrome Text app can be used to open any Mac text file, as seen in the screenshot below. The Text app shows up as an option right alongside native options like TextEdit.
It is now possible to get OS integration of file associations for Chrome Apps in Chrome Canary for Mac.Enabling this flag in Canary Chrome will let users choose installed Chrome apps as an option when opening an associated file, with the apps behaving as native Mac apps. As noted by Gigaom, the process functions through app manifests, which allow developers to specify which apps are compatible with different file types via file handlers.
All you need is to enable the experimental chrome://flags/#enable-apps-file-associations flag and restart your browser.
While the feature is currently limited to Chrome Canary for testing purposes, many Canary functions eventually make it to Google's stable Chrome browser. There is no word, however, on when the new feature might make it out of testing as there are still several bugs to work out.