Simple Timer

manifest.json

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "name": "Simple Timer",
  "version": "1.0",
  "description": "Simple timer that shows a popup when time is up.",
  "browser_action": {
    "default_title": "Timer",
    "default_icon": "timer-icon.png",
    "default_popup": "popup.html"
  },
  "background": {
    "scripts": [
      "sample.js"
    ],
    "persistent": true
  },
  "manifest_version": 2
}