Examine source code of FormSaver

{
  "description": "Save and restore form inputs",
  "manifest_version": 2,
  "name": "FormSaver",
  "version": "0.0.3resigned1",
  "icons": {
    "48": "icons/icon.svg"
  },
  "applications": {
    "gecko": {
      "id": "formsaver@gee-bee"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "form_saver.js"
      ]
    }
  ]
}