Examine source code of Plex Sleep Timer

{
  "manifest_version": 2,
  "name": "Plex Sleep Timer",
  "version": "1.0.0",
  "description": "Adds a sleep timer to Plex Web — automatically pauses playback after a set duration.",
  "author": "kolloid",
  "permissions": [
    "alarms",
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "plex-sleep-timer@kioz",
      "strict_min_version": "142.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "optional": []
      }
    },
    "gecko_android": {
      "strict_min_version": "142.0"
    }
  },
  "browser_action": {
    "default_icon": "icons/icon-48.svg",
    "default_title": "Plex Sleep Timer"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "icons": {
    "48": "icons/icon-48.svg"
  }
}