Examine source code of timeTrackerForSites

{
  "manifest_version": 2,
  "name": "Web Activity Time Tracker",
  "short_name": "Web Time Tracker",
  "version": "1.5.4",
  "minimum_chrome_version": "26",
  "description": "Track and limit time your activity in the browser every day.",
  "options_page": "options.html",
  "icons": {
    "16": "icons/16x16.png",
    "32": "icons/32x32.png",
    "48": "icons/48x48.png",
    "128": "icons/128x128.png"
  },
  "permissions": [
    "tabs",
    "activeTab",
    "storage",
    "idle",
    "chrome://favicon/*",
    "webNavigation",
    "unlimitedStorage"
  ],
  "optional_permissions": [
    "https://www.youtube.com/*",
    "https://www.netflix.com/*",
    "notifications"
  ],
  "offline_enabled": true,
  "background": {
    "scripts": [
      "scripts/common.js",
      "scripts/storage.js",
      "scripts/activity.js",
      "scripts/tab.js",
      "scripts/timeInterval.js",
      "scripts/background.js",
      "scripts/restriction.js",
      "scripts/url.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_popup": "index.html",
    "default_title": "Web Activity Time Tracker",
    "default_icon": "icons/48x48.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{4f827acc-0f21-401a-a1a2-f698d45b3cf0}"
    }
  }
}