Examine source code of Scroll Speed Controller

{
  "manifest_version": 3,
  "name": "Scroll Speed Controller",
  "version": "1.0",
  "description": "Control your scroll wheel speed across all websites",
  "browser_specific_settings": {
    "gecko": {
      "id": "scroll-speed-controller@cqs3a.addons.mozilla.org",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    },
    "permissions": [
      "activeTab",
      "storage"
    ],
    "host_permissions": [
      "<all_urls>"
    ],
    "action": {
      "default_popup": "popup.html",
      "default_title": "Scroll Speed Controller",
      "default_icon": {
        "16": "icons/icon-16.png",
        "48": "icons/icon-48.png",
        "96": "icons/icon-96.png"
      }
    },
    "content_scripts": [
      {
        "matches": [
          "<all_urls>"
        ],
        "js": [
          "content.js"
        ],
        "run_at": "document_start",
        "all_frames": false
      }
    ]
  }
}