Examine source code of Simple Time Tracker

{
  "manifest_version": 2,
  "name": "Time Tracker",
  "version": "2.0",
  "description": "Know how much time you spend on sites and get upset in your life.",
  "permissions": [
    "tabs",
    "storage",
    "activeTab",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icon.png",
      "48": "icon.png"
    }
  },
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{189ba71e-7575-4c03-9d87-a3b02f04e13b}"
    }
  }
}