Examine source code of Incognito Indicator

{
  "manifest_version": 2,
  "name": "Incognito Indicator",
  "description": "Indicate if the current tab is in incognito mode.",
  "author": "schilkyl",
  "version": "1.0.0",
  "permissions": [
    "tabs"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "icons": {
    "16": "images/incognito_on.svg"
  },
  "browser_action": {
    "default_icon": "images/incognito_default.svg"
  }
}