Examine source code of How Many Visits?

{
  "manifest_version": 2,
  "name": "How Many Visits?",
  "version": "1.2",
  "description": "Counts how many times you visited each site and shows the last visit date.",
  "icons": {
    "64": "icons/icon64.png",
    "128": "icons/icon128.png"
  },
  "permissions": [
    "tabs",
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": "icons/icon64.png",
    "default_popup": "popup.html",
    "default_title": "How Many Visits"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{ca18c8ac-7284-43e4-92c6-fa4d426a4312}",
      "strict_min_version": "127.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}