Examine source code of thisDayInHistory

{
  "manifest_version": 3,
  "name": "thisDayInHistory",
  "short_name": "thisDay",
  "version": "2.0",
  "author": "guzzMobile.com",
  "description": "Events, Births, Deaths this day in History!",
  "icons": {
    "16": "images/i16.png",
    "32": "images/i32.png",
    "48": "images/i48.png",
    "128": "images/i128.png"
  },
  "action": {
    "default_title": "thisDayInHistory",
    "default_icon": {
      "16": "images/i16.png",
      "32": "images/i32.png",
      "48": "images/i48.png",
      "128": "images/i128.png"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "thisDay@guzzmobile.com"
    },
    "gecko_android": {}
  },
  "permissions": [
    "tabs"
  ]
}