Examine source code of Search engine assistant

{
  "manifest_version": 2,
  "name": "Search engine assistant",
  "version": "1.13",
  "description": "Simply switch between search results from DuckDuckGo to results from Google or reverse in one click!",
  "icons": {
    "48": "extension.svg"
  },
  "browser_action": {
    "default_title": "Search engine assistant",
    "default_popup": "switch.html"
  },
  "permissions": [
    "activeTab"
  ]
}