Examine source code of Video Audio Extractor

{
  "manifest_version": 2,
  "name": "Video Audio Extractor",
  "version": "1.0",
  "description": "Extracts audio from videos on a webpage and saves it as an MP3 file.",
  "permissions": [
    "activeTab",
    "downloads"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "https://*/*",
        "http://*/*"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{9cc293a2-61a6-4466-a434-dfb66f2ed0d4}"
    }
  }
}