Examine source code of Block media

{
  "manifest_version": 2,
  "name": "Block media",
  "description": "Blocks fonts, images, audio, videos, and beacons from loading. Useful for automated testing for faster page loads.",
  "version": "1.2",
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "index.js"
    ],
    "persistent": true
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{d29d2dd4-d33c-4d4c-8d31-c2d06d7bbf82}"
    }
  }
}