ARC is a web-based application and it has a browser included in it. To leverage this ARC allows you to open a Chromium browser window (it is an open-source version of Chrome), log in to a web service, and store received this way cookies into ARC storage. The window opened in ARC has a separate storage and session management than any other ARC window (main application, menu popup window, task manager, and so on). This way you can securely authenticate in the window and only incoming cookies are sent back to the application ignoring any other stored values.