Examine source code of Meet Audio Auto-Select

{
  "manifest_version": 2,
  "name": "Meet Audio Auto-Select",
  "version": "1.0.0",
  "description": "Automatically uses your preferred microphone and speaker on Google Meet when they are connected.",
  "browser_specific_settings": {
    "gecko": {
      "id": "meet-audio-autoselect@extension",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "permissions": [
    "storage",
    "*://meet.google.com/*"
  ],
  "browser_action": {
    "default_title": "Meet Audio Auto-Select",
    "default_popup": "popup.html",
    "default_icon": {
      "48": "icons/icon.svg",
      "96": "icons/icon.svg"
    }
  },
  "icons": {
    "48": "icons/icon.svg",
    "96": "icons/icon.svg",
    "128": "icons/icon.svg"
  },
  "content_scripts": [
    {
      "matches": [
        "*://meet.google.com/*"
      ],
      "js": [
        "shared.js",
        "content.js"
      ],
      "run_at": "document_start"
    },
    {
      "matches": [
        "*://meet.google.com/*"
      ],
      "js": [
        "shared.js",
        "page.js"
      ],
      "run_at": "document_start",
      "world": "MAIN"
    }
  ]
}