Examine source code of RandomLemon

{
  "name": "RandomLemon",
  "version": "2.2.1",
  "manifest_version": 2,
  "description": "Adds a button that sends the user to a random LemonAmiga.com or Lemon64.com game page.",
  "homepage_url": "https://github.com/BillerNET/RandomLemonAmiga",
  "browser_action": {
    "browser_style": false,
    "default_icon": {
      "16": "icons/icon16.png",
      "32": "icons/icon32.png"
    },
    "default_title": "RandomLemon",
    "default_popup": "html/options.html"
  },
  "icons": {
    "16": "icons/icon16.png",
    "32": "icons/icon32.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "default_locale": "en",
  "permissions": [
    "*://www.lemonamiga.com/*",
    "*://www.lemon64.com/*",
    "storage"
  ],
  "web_accessible_resources": [
    "images/signz_random.gif",
    "images/c64_random.gif"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://www.lemonamiga.com/*",
        "*://www.lemon64.com/*"
      ],
      "all_frames": true,
      "js": [
        "js/RandomLemon.js"
      ],
      "css": [
        "css/RandomLemon.css"
      ]
    }
  ]
}