Examine source code of Forge Server Switcher

{
  "manifest_version": 2,
  "name": "Forge of Empires Server Switcher",
  "version": "1.12",
  "description": "Upgrade your Forge of Empires experience with smooth server switching. Made by Tigertjheu NL server.",
  "content_scripts": [
    {
      "matches": [
        "https://*.forgeofempires.com/game/index*"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "styles.css"
      ]
    }
  ],
  "icons": {
    "16": "images/icon16.png",
    "32": "images/icon32.png",
    "48": "images/icon48.png",
    "64": "images/icon64.png",
    "128": "images/icon128.png",
    "256": "images/icon256.png",
    "300": "images/icon300.png",
    "400": "images/icon400.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "jouw.extensie@voorbeeld.com"
    }
  }
}