Examine source code of Hue & Grayscale Modifier

{
  "manifest_version": 2,
  "name": "Hue & Grayscale Modifier",
  "version": "1.1",
  "description": "Customize your browsing experience by giving websites a fresh look with just a few clicks! Whether you're after a colorful hue shift or a clean grayscale effect, this extension lets you change things up quickly and effortlessly",
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "colourify/colourify.js"
      ]
    }
  ],
  "browser_action": {
    "browser_style": true,
    "default_icon": {
      "48": "/square4848.svg"
    },
    "default_title": "Colourify",
    "default_popup": "/popup/popup.html"
  },
  "permissions": [
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{b46d8e73-8956-4063-9264-de15d1e34d57}"
    }
  }
}