Examine source code of MPB Enhancer

{
  "manifest_version": 2,
  "name": "MPB Enhancer",
  "version": "1.0",
  "description": "Adds more information to the MPB website. For now it loads observations and displays them on the product list page",
  "icons": {
    "48": "icons/mb_48.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.mpb.com/*"
      ],
      "js": [
        "mb.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{486c2954-ae02-44b6-8141-6f23eed7379e}"
    }
  }
}