Examine source code of Duplicate Tab Shortcut

{
  "manifest_version": 2,
  "name": "Duplicate Tab Shortcut",
  "version": "1.7.0",
  "description": "Press Alt+Shift+D to duplicate the current tab (Option+Shift+D on Mac). Shortcut is configurable.",
  "homepage_url": "https://github.com/stefansundin/duplicate-tab",
  "author": "Stefan Sundin",
  "icons": {
    "16": "img/icon16.png",
    "48": "img/icon48.png",
    "128": "img/icon128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "options_ui": {
    "page": "popup.html"
  },
  "browser_action": {
    "default_icon": {
      "16": "img/icon16.png",
      "48": "img/icon48.png"
    },
    "default_title": "Configure Duplicate Tab Shortcut",
    "default_popup": "popup.html"
  },
  "commands": {
    "duplicate-tab": {
      "suggested_key": {
        "default": "Alt+Shift+D"
      },
      "description": "Duplicate the current tab"
    },
    "duplicate-to-new-window": {
      "description": "Duplicate to a new window"
    },
    "pop-out-to-new-window": {
      "description": "Pop tab out to a new window"
    },
    "new-tab-to-the-right": {
      "description": "New tab to the right"
    }
  },
  "permissions": [
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "duplicate-tab@firefox.stefansundin.com",
      "strict_min_version": "137.0"
    }
  }
}