Examine source code of humblextractor

{
  "manifest_version": 2,
  "name": "humblextractor",
  "version": "1.0",
  "description": "Extracts game keys from Humble Bundle.",
  "permissions": [
    "activeTab",
    "storage",
    "downloads"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_icon": {
      "48": "icons/icon.png"
    },
    "default_title": "humblextractor menu",
    "default_popup": "popup.html"
  },
  "icons": {
    "48": "icons/icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{46528a68-c2b0-4095-ad21-4e81ea8ee4df}"
    }
  }
}