Examine source code of Font Detect

{
  "manifest_version": 2,
  "name": "What Font",
  "version": "1.0.2",
  "description": "Detect font on element hover",
  "author": "Bozidar Atanasovski",
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "/scripts/page.js"
      ],
      "css": [
        "/styles/page.css"
      ]
    }
  ],
  "background": {
    "scripts": [
      "/scripts/background.js"
    ]
  },
  "browser_action": {
    "default_icon": {
      "48": "/icons/icon.png"
    },
    "default_title": "Font Detect"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{5c75bcbc-764d-497e-98fc-b541367b6128}"
    }
  }
}