Examine source code of WhatsApp Sidebar

{
  "manifest_version": 2,
  "name": "WhatsApp Sidebar",
  "version": "1.0.2",
  "description": "Open WhatsApp Web in a Firefox sidebar",
  "license": "GPL-3.0",
  "browser_specific_settings": {
    "gecko": {
      "id": "{e671ea55-fa3c-44a9-a19d-f123182e8300}"
    }
  },
  "icons": {
    "48": "src/icons/whatsapp-48.png",
    "96": "src/icons/whatsapp-96.png",
    "128": "src/icons/whatsapp-128.png",
    "256": "src/icons/whatsapp-256.png"
  },
  "background": {
    "scripts": [
      "src/background.js"
    ]
  },
  "sidebar_action": {
    "default_title": "WhatsApp",
    "default_panel": "src/ext_sidebar/sidebar.html",
    "default_icon": {
      "16": "src/icons/whatsapp-16.png",
      "32": "src/icons/whatsapp-32.png"
    }
  },
  "options_ui": {
    "page": "src/ext_options/options.html",
    "browser_style": true
  },
  "permissions": [
    "https://web.whatsapp.com/"
  ],
  "commands": {
    "_toggleSidebar": {
      "suggested_key": {
        "default": "Alt+Shift+W"
      },
      "description": "Toggle WhatsApp sidebar."
    }
  }
}