Examine source code of Enhanced

{
  "manifest_version": 2,
  "name": "Enhanced",
  "version": "1.1resigned1",
  "description": "An extension to enhance the web.",
  "icons": {
    "48": "assets/enhanced-48.png",
    "96": "assets/enhanced-96.png"
  },
  "background": {
    "scripts": [
      "src/browser-polyfill.min.js",
      "src/background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.spotify.com/fr/account/subscription/receipt*"
      ],
      "js": [
        "src/browser-polyfill.min.js",
        "src/spotify.js"
      ],
      "run_at": "document_end"
    },
    {
      "matches": [
        "https://app.payfit.com/expenses/new*"
      ],
      "js": [
        "src/browser-polyfill.min.js",
        "src/payfit.js"
      ],
      "run_at": "document_end"
    }
  ],
  "permissions": [
    "activeTab",
    "tabs",
    "<all_urls>"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{3f41dd60-06ae-4fda-9e8e-a8ee89537cd9}"
    }
  }
}