Examine source code of WordPress Detector

{
  "name": "WordPress Detector",
  "author": "bensaine",
  "version": "1.0.1",
  "description": "WordPress Detector will detect instantly if the site in your current tab is made using WordPress!",
  "permissions": [
    "activeTab",
    "tabs"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "icons": {
    "16": "icon_16.png",
    "32": "icon_32.png",
    "48": "icon_48.png",
    "128": "icon_128.png"
  },
  "manifest_version": 2,
  "browser_action": {
    "default_icon": "icon_off_32.png",
    "default_title": "WordPress Detector"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{21a16015-26a5-4449-92ae-633e2b960be7}"
    }
  }
}