Examine source code of word clock

{
  "manifest_version": 2,
  "default_locale": "en",
  "name": "__MSG_extension_name__",
  "description": "__MSG_extension_description__",
  "version": "1.0",
  "icons": {
    "1024": "images/icon.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "1024": "images/toolbar.png"
    }
  },
  "permissions": [],
  "browser_specific_settings": {
    "gecko": {
      "id": "{23db5736-ddac-480c-81d8-2384100ebadf}"
    }
  }
}