Examine source code of Disable Middle Click

{
  "manifest_version": 2,
  "name": "Disable Middle Click",
  "version": "1.0",
  "description": "A Firefox extension that disables the middle click.",
  "icons": {
    "16": "icons/icon-16.png",
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png",
    "128": "icons/icon-128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_start"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{bc7ffa57-8171-4932-ab50-bb10470ea998}"
    }
  }
}