Examine source code of Name my vote

{
  "manifest_version": 2,
  "name": "Name my vote",
  "version": "1.1.1",
  "description": "A simple firefox extension that automatically fills in your minecraft username on the popular minecraft server lists wiht a vote function. You won't never miss your reward for voting!",
  "homepage_url": "https://github.com/frommMoritz/name-my-vote/",
  "content_scripts": [
    {
      "matches": [
        "https://*.minecraft-serverlist.net/vote/*"
      ],
      "js": [
        "src/minecraft-serverlist.net.js"
      ]
    },
    {
      "matches": [
        "https://minecraft-server.eu/vote/*"
      ],
      "js": [
        "src/minecraft-server.eu.js"
      ]
    },
    {
      "matches": [
        "*://vote.kadcon.de/*"
      ],
      "js": [
        "src/vote.kadcon.de.js"
      ]
    }
  ],
  "icons": {
    "64": "icons/icon-64.png",
    "128": "icons/icon-128.png",
    "256": "icons/icon-256.png",
    "512": "icons/icon-512.png"
  },
  "options_ui": {
    "page": "options/options.html",
    "browser_style": true
  },
  "permissions": [
    "storage"
  ],
  "applications": {
    "gecko": {
      "id": "name-my-vote@moritz-fromm.de"
    }
  }
}