Examine source code of Volume Master

{
  "manifest_version": 3,
  "name": "Volume Master",
  "version": "1.1.0",
  "description": "Boost any tab's volume up to 600%. Simple, elegant audio control right in your browser.",
  "permissions": [
    "activeTab",
    "scripting",
    "storage",
    "tabs"
  ],
  "host_permissions": [
    "<all_urls>"
  ],
  "action": {
    "default_popup": "popup.html",
    "default_title": "Volume Master",
    "default_icon": {
      "16": "icons/icon16.png",
      "48": "icons/icon48.png",
      "96": "icons/icon96.png",
      "128": "icons/icon128.png"
    }
  },
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "96": "icons/icon96.png",
    "128": "icons/icon128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "volume-master@extension.local",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    },
    "gecko_android": {
      "strict_min_version": "142.0"
    }
  }
}