Examine source code of Window Colour Picker

{
  "manifest_version": 2,
  "name": "Window Colour Picker",
  "version": "2.0",
  "description": "Customise your Firefox window colours with a colour picker",
  "homepage_url": "https://github.com/DaveDuck321/Colorful-window-theme",
  "icons": {
    "128": "icon.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "tabs",
    "theme",
    "storage"
  ],
  "browser_action": {
    "default_title": "Pick window colour",
    "default_popup": "popup.html",
    "default_icon": {
      "128": "icon.png"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{f0a9617b-4d04-4150-a0fc-26a5cc11d191}"
    }
  }
}