Examine source code of Tab Session Counter

{
  "manifest_version": 2,
  "name": "Tab Session Counter",
  "version": "1.0",
  "description": "Tracks the total number of tabs opened during a browsing session.",
  "permissions": [
    "tabs",
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{4813d6e8-7445-4450-bb2a-e1363d2aa5ab}"
    }
  }
}