Examine source code of Permission Inspector

{
  "manifest_version": 2,
  "name": "Permission Inspector",
  "description": "__MSG_extensionDescription__",
  "default_locale": "en",
  "version": "1.0.3",
  "icons": {
    "64": "icons/icon_64.png"
  },
  "background": {
    "scripts": [
      "background_script.js"
    ]
  },
  "browser_action": {
    "default_icon": {
      "64": "icons/icon_64.png"
    },
    "default_title": "__MSG_browserActionText__"
  },
  "permissions": [
    "management"
  ],
  "applications": {
    "gecko": {
      "id": "permissionInspector@web-ext-labs",
      "strict_min_version": "55.0"
    }
  }
}