Examine source code of Injecto

{
  "manifest_version": 2,
  "name": "Injecto",
  "version": "0.2.2",
  "description": "Inject JavaScript and CSS into websites",
  "icons": {
    "48": "icons/injecto-48.png"
  },
  "permissions": [
    "storage",
    "<all_urls>"
  ],
  "browser_action": {
    "default_icon": "icons/injecto-48.png",
    "default_title": "Injecto"
  },
  "options_ui": {
    "page": "options/index.html",
    "open_in_tab": true
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "injecto@sogomn"
    }
  },
  "background": {
    "scripts": [
      "injecto.js"
    ],
    "persistent": true
  }
}