Examine source code of Close Active Tab

{
  "author": "tedl57",
  "manifest_version": 2,
  "name": "Close Active Tab",
  "description": "Close the Active Tab.",
  "version": "0.0.1",
  "browser_specific_settings": {
    "gecko": {
      "id": "{b14fd70c-5aa5-4be8-afbd-84820c259306}"
    }
  },
  "icons": {
    "64": "icon.png"
  },
  "background": {
    "scripts": [
      "background_script.js"
    ]
  },
  "browser_action": {
    "default_area": "navbar"
  },
  "permissions": [
    "activeTab"
  ]
}