Examine source code of SalesforceProductionWarning

{
  "manifest_version": 2,
  "name": "SalesforceProductionWarning",
  "version": "1.5.6",
  "description": "Add a border on Screen to notify the environment that be operating is Production!",
  "icons": {
    "16": "icons/favicon.png",
    "48": "icons/favicon48.png",
    "128": "icons/favicon128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.salesforce.com/*",
        "*://*.visual.force.com/*",
        "*://*.lightning.force.com/*",
        "*://*.visualforce.com/*"
      ],
      "js": [
        "border.js"
      ]
    }
  ],
  "applications": {
    "gecko": {
      "id": "{672023cc-1811-46f3-9681-8e1ed7b04217}",
      "strict_min_version": "55.0"
    }
  },
  "browser_action": {
    "default_icon": "icons/favicon.png",
    "default_title": "SPWSettings",
    "default_popup": "popup/action.html"
  },
  "options_ui": {
    "page": "options.html",
    "browser_style": true,
    "open_in_tab": true
  },
  "permissions": [
    "storage"
  ]
}