Examine source code of Chess.by

{
  "manifest_version": 2,
  "name": "Chess.by",
  "version": "1.0",
  "description": "Fixes Belarusian flags on chess.com",
  "icons": {
    "48": "icons/Flag_of_Belarus.svg"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.chess.com/*"
      ],
      "js": [
        "chessby.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{666d33ef-1a57-492e-a759-2db59b55a11f}"
    }
  }
}