Examine source code of PageRank Display

{
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": "img/icon128.png",
    "default_popup": "popup.html",
    "default_title": "Page has no PR"
  },
  "description": "Displays the PageRank of open page with icon and badge. Quick access to Alexa, backlinks and indexed pages in the popup.",
  "icons": {
    "128": "img/icon128.png"
  },
  "manifest_version": 2,
  "name": "PageRank Display",
  "permissions": [
    "tabs",
    "http://toolbarqueries.google.com/"
  ],
  "version": "2.5",
  "browser_specific_settings": {
    "gecko": {
      "id": "{be98fbe7-d571-4ff0-a7eb-4f158fead010}"
    }
  }
}