Examine source code of RobloxRatio

{
  "manifest_version": 2,
  "name": "RobloxRatio",
  "version": "1.2",
  "description": "Shows precise like/dislike ratio in game page on Roblox",
  "browser_action": {
    "default_icon": {
      "48": "icons/icon.png"
    }
  },
  "icons": {
    "48": "icons/icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "robloxratio@mashiusam.com"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.roblox.com/games/*"
      ],
      "js": [
        "main.js"
      ]
    }
  ]
}