Examine source code of HeadingLinker

{
  "manifest_version": 2,
  "name": "Linker",
  "version": "1.2",
  "description": "Adds a clickable # link to quickly reference any page heading",
  "content_scripts": [
    {
      "js": [
        "linker.js"
      ],
      "matches": [
        "http://*/*",
        "https://*/*"
      ]
    }
  ],
  "icons": {
    "48": "icons/48.png",
    "96": "icons/96.png"
  }
}