Examine source code of URL2QRCode

{
  "manifest_version": 2,
  "name": "URL2QRCode",
  "description": "Converts Current URL to QRCode.",
  "author": "skyfox",
  "version": "0.2resigned1",
  "icons": {
    "32": "data/images.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "page_action": {
    "browser_style": true,
    "default_icon": {
      "32": "data/images.png"
    },
    "default_title": "Click to convert URL to QRCode",
    "default_popup": "data/index.html"
  },
  "permissions": [
    "tabs",
    "activeTab",
    "notifications",
    "contextMenus",
    "<all_urls>"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{0bacf5fd-b809-4b5d-877d-48866ec8f8e8}"
    }
  }
}