Examine source code of Watch Sniper

{
  "manifest_version": 2,
  "name": "Watch Sniper",
  "version": "1.0.0",
  "description": "Automatically refreshes Chrono24 searches sorted by Newest and plays a sound when a new listing appears.",
  "permissions": [
    "alarms",
    "tabs",
    "storage",
    "https://www.chrono24.com/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "browser_action": {
    "default_title": "Watch Sniper"
  },
  "icons": {
    "16": "watchicon16.png",
    "48": "watchicon48.png",
    "128": "watchicon128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.chrono24.com/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "web_accessible_resources": [
    "ding.wav"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "watchsniper@brighterecommerce.com",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}