Examine source code of Comparium browser testing

{
  "name": "Comparium ultimate cross browser testing tool",
  "description": "Check how your website looks and works under any operating system, browser and its version.",
  "version": "1.2",
  "manifest_version": 2,
  "permissions": [
    "tabs",
    "storage"
  ],
  "browser_action": {
    "default_popup": "index.html",
    "default_icon": {
      "16": "extension_logo16.png",
      "32": "extension_logo32.png",
      "48": "extension_logo48.png",
      "128": "extension_logo128.png"
    }
  },
  "icons": {
    "16": "extension_logo16.png",
    "32": "extension_logo32.png",
    "48": "extension_logo48.png",
    "128": "extension_logo128.png"
  },
  "web_accessible_resources": [
    "extension_logo16.png",
    "extension_logo32.png",
    "extension_logo48.png",
    "extension_logo128.png",
    "index.html"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{08998d3a-c56e-4499-ba73-0d980c7cdd96}"
    }
  }
}