Examine source code of tagEveryone(deprecated)

{
  "manifest_version": 2,
  "name": "@everyone",
  "version": "2.4",
  "homepage_url": "https://github.com/Amit0617/tagEveryone",
  "description": "Tags Everyone in a WhatsApp group",
  "icons": {
    "48": "icons/everyone-48.png",
    "96": "icons/everyone-96.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://web.whatsapp.com/"
      ],
      "js": [
        "/content_scripts/tagging.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "onboard.js"
    ]
  },
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_icon": "icons/everyone-32.png",
    "default_title": "tagEveryone!",
    "default_popup": "popup/popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{5d00b2d2-d426-40da-bd79-9f29b70abb9b}"
    }
  }
}