Examine source code of CurrenturlTimer

{
  "manifest_version": 2,
  "name": "Currenturl",
  "description": "Fetches current tab url.",
  "version": "0.1",
  "author": "A code newbie",
  "browser_action": {
    "default_icon": "icon.png",
    "default_title": "Just observing your current url."
  },
  "permissions": [
    "tabs",
    "activeTab",
    "http://127.0.0.1:5000/*",
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{fd2aed81-3990-44e0-9325-a56c70634131}"
    }
  }
}