Examine source code of Volume Booster

{
  "manifest_version": 3,
  "name": "Volume Booster",
  "version": "1.0",
  "description": "Boost the volume of the current tab.",
  "permissions": [
    "activeTab"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "icons": {
    "16": "icons/icon16.png"
  },
  "action": {
    "default_popup": "popup.html",
    "default_icon": "icons/icon16.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "volume-booster@example.com"
    }
  }
}