Examine source code of Task Countdown Timer

{
  "manifest_version": 2,
  "name": "CountDown Timer",
  "author": "Mohamed Hafez",
  "version": "1.0.0",
  "description": "CountDown.",
  "icons": {
    "128": "stopwatch.png"
  },
  "chrome_url_overrides": {
    "newtab": "index.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{e1320e07-3b7a-4185-8ccd-79863c025346}"
    }
  }
}