Examine source code of Indic-En

{
  "manifest_version": 2,
  "name": "Indic-En",
  "version": "3.0.1",
  "icons": {
    "16": "assets/icons/favicon-16.png",
    "32": "assets/icons/favicon-32.png",
    "48": "assets/icons/favicon-48.png",
    "128": "assets/icons/favicon-128.png"
  },
  "description": "Convert Malayalam, Hindi, Kannada webpages to Manglish, Hinglish, Kanglish.",
  "homepage_url": "https://subinsb.com/indicen",
  "short_name": "Indic-En",
  "permissions": [
    "activeTab",
    "storage",
    "http://*/*",
    "https://*/*"
  ],
  "content_security_policy": "script-src 'self'; object-src 'self'",
  "author": "subins2000",
  "applications": {
    "gecko": {
      "id": "{54379e53-91f8-4ab1-b8fa-18a7a7f1424b}"
    }
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "assets/icons/favicon-16.png",
      "32": "assets/icons/favicon-32.png",
      "48": "assets/icons/favicon-48.png",
      "128": "assets/icons/favicon-128.png"
    },
    "default_title": "Indic-En",
    "browser_style": false
  },
  "options_ui": {
    "page": "options.html",
    "open_in_tab": true
  },
  "background": {
    "scripts": [
      "js/background.bundle.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "http://*/*",
        "https://*/*",
        "file://*/*"
      ],
      "js": [
        "js/contentScript.bundle.js"
      ],
      "css": [
        "css/contentScript.css"
      ]
    }
  ]
}