Examine source code of Close Other Windows

{
  "manifest_version": 2,
  "name": "Close Other Windows",
  "version": "0.2resigned1",
  "description": "Adds a button to close all tabs in other windows which are not pinned",
  "icons": {
    "32": "x32.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": "x32.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{fab4ea0f-e0d3-4bb4-9515-aea14d709f69}"
    }
  }
}