Examine source code of Clean the mess!

{
  "manifest_version": 2,
  "name": "Clean the mess",
  "version": "2.1.0",
  "author": "Tomas Hartman",
  "description": "Helps with maintaining order within once opened and never-seen-again tabs as well with those visited way too often.",
  "permissions": [
    "tabs",
    "bookmarks",
    "storage"
  ],
  "background": {
    "scripts": [
      "background.daa40348.js"
    ]
  },
  "options_ui": {
    "page": "options.ce26e91e.html",
    "browser_style": true
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{324a28fc-ef5d-4e34-aaff-28dacd65b97c}"
    }
  },
  "icons": {
    "16": "ico-light-16.007e937a.png",
    "32": "ico-light-32.b4d1fbcc.png",
    "128": "ico-light-128.8af71d39.png"
  },
  "browser_action": {
    "browser_style": false,
    "default_icon": {
      "16": "ico-light-16.007e937a.png",
      "32": "ico-light-32.b4d1fbcc.png",
      "128": "ico-light-128.8af71d39.png"
    },
    "default_title": "Clean the mess",
    "default_popup": "popup.121f468c.html",
    "theme_icons": [
      {
        "dark": "ico-light-16.007e937a.png",
        "light": "ico-dark-16.27a613a2.png",
        "size": 16
      },
      {
        "dark": "ico-light-32.b4d1fbcc.png",
        "light": "ico-dark-32.daca4865.png",
        "size": 32
      },
      {
        "dark": "ico-light-128.8af71d39.png",
        "light": "ico-dark-128.a3346686.png",
        "size": 128
      }
    ]
  },
  "commands": {
    "_execute_browser_action": {
      "suggested_key": {
        "default": "Ctrl+Alt+T",
        "mac": "Ctrl+Alt+T"
      },
      "description": "Open extension popup"
    }
  }
}