Examine source code of EbayNoNewTab

{
  "manifest_version": 2,
  "name": "EbayNoNewTab",
  "version": "1.0",
  "description": "Ebay opens a new tab on click. Very annoying.",
  "content_scripts": [
    {
      "matches": [
        "*://*.ebay.com/sch/*"
      ],
      "js": [
        "nonewtab.js"
      ]
    }
  ]
}