Examine source code of Page Element Counter

{
  "manifest_version": 2,
  "name": "Page Element Counter",
  "version": "1.0.0",
  "description": "Analyze webpage structure by counting HTML elements, images, links, forms and more",
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_title": "Page Element Counter",
    "default_icon": {
      "16": "icon16.png",
      "48": "icon48.png",
      "128": "icon128.png"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "icons": {
    "16": "icon16.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{5f67dd3b-d24c-4d12-bc6f-4ad7c22f2165}"
    }
  }
}