Examine source code of Duolingo TTS Controls

{
  "name": "Duolingo TTS Controls",
  "version": "2.7.3",
  "description": "Provides playback controls for some of the challenges on Duolingo.",
  "permissions": [
    "https://*.duolingo.com/"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://*.duolingo.com/*"
      ],
      "js": [
        "src/content.js"
      ],
      "run_at": "document_start"
    }
  ],
  "web_accessible_resources": [
    "src/observer.js",
    "src/ui.js",
    "assets/css/ui.css"
  ],
  "icons": {
    "16": "icons/icon_16.png",
    "48": "icons/icon_48.png",
    "128": "icons/icon_128.png",
    "256": "icons/icon_256.png",
    "512": "icons/icon_512.png"
  },
  "manifest_version": 2,
  "browser_specific_settings": {
    "gecko": {
      "id": "{5366e4f5-05b9-42d2-9d91-1593ea5cb83c}"
    }
  }
}