Examine source code of input-dropdown-replacer

{
  "manifest_version": 2,
  "name": "input-dropdown-replacer",
  "version": "1.0.0.1",
  "description": "Replaces all text input with dropdowns",
  "icons": {
    "48": "icons/input-dropdown-48.png",
    "96": "icons/input-dropdown-96.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "dropdown.js"
      ]
    }
  ]
}