Examine source code of Tab Time Tracker

{
  "manifest_version": 2,
  "name": "Tab Time Tracker",
  "version": "1.0",
  "description": "Track and display the time spent on each open tab during the current browsing session.",
  "permissions": [
    "tabs",
    "activeTab",
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{4270d93d-9c69-4f4f-bece-7ebd4aa2df68}"
    }
  }
}