Examine source code of Check Browsers Support

{
  "manifest_version": 2,
  "name": "CheckBrowsersSupport",
  "description": "A browser extension to check if a given web technology is supported by browsers",
  "author": "Phuoc Nguyen",
  "version": "1.0.0",
  "homepage_url": "https://checkbrowsers.support",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": {
      "24": "images/icon-24.png",
      "48": "images/icon-48.png",
      "96": "images/icon-96.png",
      "512": "images/icon-512.png"
    },
    "default_title": "Check Browsers Support"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "css": [
        "browsers-support.min.css"
      ],
      "js": [
        "content.js",
        "browsers-support.min.js"
      ],
      "run_at": "document_end"
    }
  ],
  "icons": {
    "24": "images/icon-24.png",
    "48": "images/icon-48.png"
  },
  "permissions": [
    "activeTab",
    "contextMenus",
    "storage",
    "https://api.gumroad.com/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "hi@checkbrowsers.support",
      "strict_min_version": "55.0"
    }
  }
}