Examine source code of Form Autofiller

{
  "manifest_version": 2,
  "name": "Form Autofiller",
  "version": "1.0",
  "description": "Save and autofill form templates quickly.",
  "permissions": [
    "storage",
    "activeTab",
    "tabs"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_title": "Autofill Form"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{5d4a2910-7855-4bb2-9226-41bebf15d22b}"
    }
  }
}