Examine source code of Onliner Compare

{
  "manifest_version": 2,
  "name": "Onliner Compare",
  "version": "1.0",
  "description": "extention for Onliner",
  "icons": {
    "192": "onl.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      },
      "id": "{498456d7-bca2-4f11-8db3-94cdfb903821}"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "*://catalog.onliner.by/compare/*"
      ],
      "js": [
        "main.js"
      ]
    }
  ]
}