Examine source code of run-a-script

{
  "description": "Allows you to define exactly one JS script and inject it into every web page you visit. It uses Firefox' userScripts feature which allows the sandboxed execution of user-defined scripts. For some convienience, jQuery is usable from your code. The code base is only a couple of lines so you can quickly check for security foul play. A critical tool in the fight against the modern internet.",
  "manifest_version": 2,
  "name": "run-a-script",
  "version": "1.0.2",
  "homepage_url": "https://github.com/MIvanchev/run-a-script",
  "icons": {
    "16": "icons/doge.svg",
    "32": "icons/doge.svg",
    "48": "icons/doge.svg",
    "64": "icons/doge.svg",
    "96": "icons/doge.svg"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "user_scripts": {},
  "options_ui": {
    "page": "settings.html"
  },
  "browser_action": {
    "browser_style": true,
    "default_popup": "settings.html",
    "default_icon": {
      "32": "icons/doge-32.png",
      "48": "icons/doge-48.png",
      "64": "icons/doge.svg",
      "96": "icons/doge.svg"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "run-a-script@ivanchev.net",
      "strict_min_version": "68.0"
    }
  },
  "permissions": [
    "storage",
    "<all_urls>"
  ]
}