Examine source code of Mute Tab Toggle

{
  "manifest_version": 2,
  "name": "Mute Tab Toggle",
  "version": "1.0",
  "description": "Toggle mute/unmute on the current tab with one click.",
  "permissions": [
    "tabs"
  ],
  "browser_action": {
    "default_icon": "icon.png",
    "default_title": "Toggle Mute",
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{f90f34de-456b-42c0-9872-b69c616c2f87}"
    }
  }
}