Examine source code of RGB Progress Bar

{
  "manifest_version": 2,
  "name": "RGB Progress Bar",
  "version": "4.5.3",
  "author": "Array in a Matrix",
  "developer": {
    "name": "Array in a Matrix",
    "url": "https://arrayinamatrix.xyz"
  },
  "description": "Makes progress bars cycle through different RGB colors.",
  "browser_specific_settings": {
    "gecko": {
      "id": "tensor@arrayinamatrix.xyz",
      "strict_min_version": "58.0"
    }
  },
  "icons": {
    "48": "icons/icon-48.jpg",
    "96": "icons/icon-96.jpg"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "css": [
        "style.css"
      ]
    }
  ]
}