Examine source code of Viki Volume Control

{
  "name": "Viki Volume Control",
  "version": "1.0.0",
  "author": "zvbt",
  "manifest_version": 3,
  "description": "Viki extension to control volume with the mouse wheel.",
  "homepage_url": "https://github.com/zvbt/Viki-Volume-Control",
  "icons": {
    "128": "icons/icon128.png"
  },
  "action": {
    "default_icon": "icons/icon128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.viki.com/*"
      ],
      "js": [
        "src/viki.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "zvbt@akali.best",
      "strict_min_version": "42.0"
    }
  },
  "host_permissions": [
    "*://*.viki.com/"
  ]
}