[models/file] Provide a callback for saving a file we are downloading.
[models/file] Provide a callback for saving a file we are downloading.

nylas/inbox-scaffold-html5,PriviPK/privipk-webapp,Eagles2F/inbox-scaffold-html5,PriviPK/privipk-webapp,nylas/inbox-scaffold-html5,Eagles2F/inbox-scaffold-html5,PriviPK/privipk-webapp,Eagles2F/inbox-scaffold-html5,PriviPK/privipk-webapp,nylas/inbox-scaffold-html5