Examine source code of Word up!

{
  "manifest_version": 2,
  "version": "0.2.3resigned1",
  "name": "Word up!",
  "description": "Double-click a word to see its definition (from Wordnik).",
  "developer": {
    "name": "Viktor Voropaev",
    "url": "http://vorou.com"
  },
  "icons": {
    "48": "wordup-48.png",
    "64": "wordup-64.png",
    "96": "wordup-96.png",
    "128": "wordup-128.png"
  },
  "permissions": [
    "*://api.wordnik.com/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "content.css"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{9021145f-8d5e-4982-8a52-df9a4a47e03e}"
    }
  }
}