Examine source code of Global Grayscale

{
  "manifest_version": 3,
  "name": "Global Grayscale",
  "version": "4.0",
  "description": "Globally synced grayscale for all tabs and UI.",
  "permissions": [
    "scripting",
    "theme",
    "storage"
  ],
  "icons": {
    "16": "icons/grayscale-logo-16.png",
    "48": "icons/grayscale-logo-48.png",
    "128": "icons/grayscale-logo-128.png"
  },
  "action": {
    "default_title": "Toggle Global Grayscale",
    "default_icon": "icons/grayscale-logo-16.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_start"
    }
  ],
  "homepage_url": "https://github.com/adminchev/Grayscale-for-Firefox",
  "browser_specific_settings": {
    "gecko": {
      "id": "grayscale@adminchev",
      "strict_min_version": "115.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}