Examine source code of Freelancer Helper Exp

{
  "description": "Improvements for freelancer.com. Hiding projects by country, showing employer details...",
  "version": "1.4.2.0",
  "name": "Freelancer Helper",
  "permissions": [
    "activeTab",
    "storage",
    "alarms",
    "identity",
    "declarativeNetRequest",
    "tabs",
    "*://*.freelancer.com/*"
  ],
  "background": {
    "scripts": [
      "background.bundle.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_title": "Freelancer Helper",
    "default_icon": {
      "16": "public/icon_128.png",
      "48": "public/icon_128.png",
      "128": "public/icon_128.png"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.freelancer.com/*"
      ],
      "run_at": "document_start",
      "js": [
        "whole.bundle.js"
      ]
    }
  ],
  "icons": {
    "16": "public/icon_128.png",
    "48": "public/icon_128.png",
    "128": "public/icon_128.png"
  },
  "web_accessible_resources": [
    "public/*.json"
  ],
  "oauth2": {
    "client_id": "668183917517-o23qa61l3ooievsc736p8f5ucaf6od03.apps.googleusercontent.com",
    "scopes": [
      "email"
    ]
  },
  "manifest_version": 2,
  "content_security_policy": "script-src 'self'; object-src 'self'",
  "browser_specific_settings": {
    "gecko": {
      "id": "{1ccfa40c-5062-4554-8bfc-f270da5a7a6c}"
    }
  }
}