[ { "namespace": "manifest", "types": [ { "$extend": "WebExtensionManifest", "properties": { "devtools_page": { "$ref": "ExtensionURL", "optional": true } } }, { "$extend": "OptionalPermission", "choices": [{ "type": "string", "enum": [ "devtools" ] }] } ] }, { "namespace": "devtools", "permissions": ["manifest:devtools_page"], "allowedContexts": ["devtools", "devtools_only"], "defaultContexts": ["devtools", "devtools_only"] } ]