Examine source code of The Free Dictionary

{
  "manifest_version": 2,
  "name": "Dictionary",
  "version": "2.2resigned1",
  "description": "Double-click a word on any website and instantly get its definition at TheFreeDictionary, the world's most comprehensive dictionary!",
  "icons": {
    "16": "/img/icon16.png",
    "19": "/img/icon19.png",
    "38": "/img/icon38.png",
    "48": "/img/icon48.png"
  },
  "browser_action": {
    "default_icon": "/img/icon48.png",
    "default_title": "Get definition from TheFreeDictionary.com, the world's most comprehensive dictionary",
    "default_popup": "popup.htm"
  },
  "background": {
    "scripts": [
      "js/background.js"
    ]
  },
  "permissions": [
    "tabs",
    "contextMenus"
  ],
  "homepage_url": "http://thefreedictionary.com",
  "content_scripts": [
    {
      "js": [
        "js/content.js"
      ],
      "matches": [
        "http://*/*",
        "https://*/*"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{ad9db098-76c1-4867-a7e5-c570dfb70c3e}"
    }
  }
}