Examine source code of Merge Windows

{
  "name": "Merge Windows",
  "version": "2.9.9",
  "description": "Merges all of the browser's windows into the current window",
  "icons": {
    "48": "merge_windows_48.png",
    "128": "merge_windows_128.png"
  },
  "background": {
    "persistent": false,
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": "arrow_in.png",
    "default_title": "Merge Windows"
  },
  "manifest_version": 2,
  "browser_specific_settings": {
    "gecko": {
      "id": "{27d47acd-04aa-410e-9a26-c14811ba6b2d}"
    }
  }
}