Examine source code of Spokal

{
  "background": {
    "persistent": false,
    "scripts": [
      "includes/background.js"
    ]
  },
  "browser_action": {
    "default_icon": {
      "19": "icons/icon_19.png",
      "32": "icons/icon-32.png",
      "38": "icons/icon_38.png"
    },
    "default_popup": "popup/popup.html"
  },
  "description": "Share to Twitter, Facebook & LinkedIn with automatic, recurring scheduling.",
  "icons": {
    "16": "icons/icon_16.png",
    "48": "icons/icon_48.png",
    "96": "icons/icon-96.png",
    "128": "icons/icon_128.png"
  },
  "web_accessible_resources": [
    "icons/spinner.gif"
  ],
  "manifest_version": 2,
  "name": "Spokal",
  "permissions": [
    "tabs",
    "activeTab"
  ],
  "version": "1.2.1resigned1",
  "browser_specific_settings": {
    "gecko": {
      "id": "@spokal"
    }
  }
}