Examine source code of Whatsapp Web Designer

{
  "name": "__MSG_extName__",
  "description": "__MSG_extDescription__",
  "version": "1.6.4",
  "manifest_version": 2,
  "browser_action": {
    "default_popup": "popup/create_tab.html",
    "default_icon": {
      "16": "assets/default_icon/WhatsApp_icon-16.png",
      "32": "assets/default_icon/WhatsApp_icon-32.png",
      "48": "assets/default_icon/WhatsApp_icon-48.png",
      "128": "assets/default_icon/WhatsApp_icon-128.png"
    },
    "default_title": "__MSG_popupTitle__"
  },
  "author": "omarg60@yahoo.com",
  "short_name": "WAW Designer",
  "browser_specific_settings": {
    "gecko": {
      "id": "Whatsapp_Web_Designer@goosemugger.com",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "permissions": [
    "storage",
    "https://web.whatsapp.com/*"
  ],
  "default_locale": "en",
  "content_scripts": [
    {
      "js": [
        "content_scripts/bundle_0.js"
      ],
      "css": [
        "content_scripts/static/static.css"
      ],
      "matches": [
        "https://web.whatsapp.com/*"
      ],
      "run_at": "document_start"
    },
    {
      "js": [
        "content_scripts/bundle_1.js"
      ],
      "matches": [
        "https://web.whatsapp.com/*"
      ],
      "world": "MAIN",
      "run_at": "document_start"
    }
  ],
  "background": {
    "scripts": [
      "service_worker.js"
    ]
  },
  "web_accessible_resources": [
    "popup/create_tab.html",
    "popup/actions.html",
    "popup/new_actions.html",
    "content_scripts/features/themes/styles.css",
    "content_scripts/static_data/static.css",
    "content_scripts/static_data/override_audio.js",
    "content_scripts/static_data/bg_freak_page.js",
    "assets/audios/*.mp3",
    "assets/default_icon/*.png"
  ],
  "icons": {
    "16": "assets/default_icon/WhatsApp_icon-16.png",
    "32": "assets/default_icon/WhatsApp_icon-32.png",
    "48": "assets/default_icon/WhatsApp_icon-48.png",
    "128": "assets/default_icon/WhatsApp_icon-128.png"
  }
}