Click here to read a TechRepublic article "ChromeOS offers a new feature to give you quick access to your often-used files" that shows you how to use this handy feature.
Click here to read another good overview at Google's Blog
The Tote feature provides fast access to recent files and incorporates the File Manager and Downloads subsystems.
The key Tote features are :
Downloaded files that can be easily accessed from the system tray
Files that can be pinned to the Tote notification popup
Files that can be dragged from the File Manager into Tote
File previews that are directly accessed from the Tote popup