Examine source code of Click Button By XPath

{
  "manifest_version": 2,
  "name": "Click Button By XPath",
  "version": "1.0.0",
  "description": "A Firefox extension that clicks a button based on a relative XPath",
  "icons": {
    "48": "icon48.png"
  },
  "permissions": [
    "activeTab"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content-script.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{b7c960cc-a1df-4e67-b523-b6bac16156f8}"
    }
  }
}