Examine source code of Mouse Navigation Enhancer

{
  "manifest_version": 2,
  "name": "Mouse Navigation Enhancer",
  "version": "1.0",
  "description": "Enables mouse navigation using extra buttons, allowing you to move forward and backward in your browser more efficiently",
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "mousebuttons.user.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{f5585c26-1bdb-42a6-a282-9449b15b8210}"
    }
  }
}