An enumeration that indicates how the script came to be installed as an add-on for the current user.
To call an enum, you call its parent class, name, and property. For example, 
ScriptApp.InstallationSource.APPS_MARKETPLACE_DOMAIN_ADD_ON.
Properties
| Property | Type | Description | 
|---|---|---|
| APPS_MARKETPLACE_DOMAIN_ADD_ON | Enum | Add-on was installed by the administrator for the user's domain. | 
| NONE | Enum | Script is not running as an add-on. | 
| WEB_STORE_ADD_ON | Enum | Add-on was installed by the user from the Chrome Web Store. |