Examine source code of Clean Print Mode

{
  "manifest_version": 2,
  "name": "Clean Print Mode",
  "version": "1.0",
  "description": "Tự động ẩn header, footer, sidebar, quảng cáo khi in trang web.",
  "permissions": [
    "activeTab"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_title": "Clean Print Mode"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_end"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{98f13e04-bb06-4c2a-9c7a-35b736ed1693}"
    }
  }
}