Manifest - Offline Enabled
Whether the app or extension is expected to work offline. When Chrome detects that it is offline, apps with this field set to true will be highlighted on the New Tab page.
As of Chrome 35, apps are assumed to be offline enabled and the default value
permission is requested. In this case, network connectivity is assumed to be
"offline_enabled" defaults to
"offline_enabled" value is also used to determine whether a
network connectivity check will be performed when launching an app in
Chrome OS kiosk mode. A network connectivity check will be performed when
apps are not offline enabled, and app launching put on hold until the device
obtains connectivity to the Internet.