manifest.merge.json

{
    "applications": {
        "gecko": {
            "id": "safelinks-cleaner@it.liu.se",
            "strict_min_version": "78.4.0"
        }
    },
    "background": {
        "scripts": [
            "background.js"
        ]
    },
    "permissions": [
	"messagesModify",
	"compose"
    ]
}