Examine source code of CSS Unit Converter

{
  "manifest_version": 2,
  "name": "CSS Unit Converter",
  "version": "1.0",
  "description": "A sleek black-and-white CSS Unit Converter.",
  "icons": {
    "48": "icons/icon.png"
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icons/icon.png"
  },
  "permissions": [
    "activeTab"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{b6277a53-2622-4486-b676-eb771785f6d6}"
    }
  }
}