Examine source code of Persistent Mute Site

{
  "manifest_version": 2,
  "name": "Persistent Mute Site",
  "version": "1.0",
  "description": "Allows to instantly mute/unmute all tabs from a website. Will remember your muted sites even after browser restart.",
  "icons": {
    "48": "icons/unmute.svg",
    "96": "icons/unmute.svg"
  },
  "permissions": [
    "tabs",
    "menus",
    "storage"
  ],
  "page_action": {
    "default_icon": "icons/unmute.svg",
    "default_title": "Toggle Mute Site"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "@persistent-mute",
      "data_collection_permissions": {
        "required": [
          "browsingActivity"
        ]
      }
    }
  }
}