Examine source code of Website Time Tracker

{
  "manifest_version": 2,
  "name": "Website Time Tracker",
  "version": "1.0",
  "description": "Sets a timer for how long you can spend on certain websites before being alerted.",
  "permissions": [
    "storage",
    "tabs",
    "webNavigation",
    "https://*/*",
    "http://*/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "browser_action": {
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "https://*/*",
        "http://*/*"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{83d2b9ca-7cf3-4908-9341-5c8c6acc1c65}"
    }
  }
}