Examine source code of fullscreenify

{
  "description": "Demonstrating toolbar buttons",
  "manifest_version": 2,
  "name": "fullscreenify",
  "version": "1.1resigned1",
  "background": {
    "scripts": [
      "fullscreenify.js"
    ]
  },
  "browser_action": {
    "default_icon": {
      "16": "icons/full-16.png",
      "32": "icons/full-32.png"
    }
  },
  "permissions": [
    "<all_urls>"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{26d7edec-6ed6-4d4e-9f8d-2562e3e103b3}"
    }
  }
}