Examine source code of Close current tab

{
  "manifest_version": 2,
  "name": "Close current tab",
  "version": "1.0.2resigned1",
  "description": "Adds button to close current tab.",
  "icons": {
    "48": "icons/icon.png"
  },
  "browser_action": {
    "default_area": "tabstrip",
    "default_icon": "icons/icon.png",
    "default_title": "Close current tab"
  },
  "background": {
    "scripts": [
      "close_current_tab.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{68a19ea4-3ca5-4b49-a2b9-7a010a19b73c}"
    }
  }
}