Google has rolled out a behind-the-scenes update that enabled comment notifications in Chrome and on Android for Google Docs, Google Sheets and Google Slides. Previously, when someone made a comment on a shared file, you would receive an email notification that the comment had been made on the document. Now you will get a standard notification on your Android devices or in Chrome when these comments have been made on the file.
The nice thing is that there is nothing really for you as an end user to change. If you have enabled notifications in Google Drive as well as Docs, Sheets and Slides, you will start getting these
notifications automatically. Keep in mind though, if you want to have these notifications come to your Chrome browser, you have to enable them as they are off by default. You can do this by going to the settings in Google Drive on the web and enabling notifications. Also make sure that you have the latest version of Google Drive for Android. The notifications will only work on the latest build (released last week).
The roll out of this new feature is happening now and it should be to everyone in the next 1-3 days per the release notice.