Examine source code of Clean Reader

{
  "manifest_version": 2,
  "name": "Clean Reader",
  "version": "1.0",
  "description": "Cleans up the web page",
  "permissions": [
    "activeTab",
    "<all_urls>"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icons/icon.png"
    }
  },
  "icons": {
    "16": "icons/icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{e701c130-d4c2-4f62-bf21-dc4fb69f7931}"
    }
  }
}