Examine source code of Custom CSS/JS Injector

{
  "manifest_version": 2,
  "name": "Custom CSS/JS Injector",
  "version": "1.0",
  "description": "Inject custom CSS and JavaScript into the current webpage.",
  "icons": {
    "48": "icon.png"
  },
  "permissions": [
    "activeTab",
    "storage"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{33e3bd59-c1de-4b16-8764-38b8dca893af}"
    }
  }
}