Examine source code of CORS Unblock

{
  "manifest_version": 3,
  "name": "CORS Unblock",
  "description": "Web apps cross-origin access with precise domain control and simple permissions.",
  "version": "0.3.1",
  "icons": {
    "16": "icon/16.png",
    "32": "icon/32.png",
    "48": "icon/48.png",
    "96": "icon/96.png",
    "128": "icon/128.png"
  },
  "permissions": [
    "storage",
    "tabs",
    "declarativeNetRequest"
  ],
  "host_permissions": [
    "https://*/*",
    "http://*/*"
  ],
  "web_accessible_resources": [
    {
      "resources": [
        "inject.js"
      ],
      "matches": [
        "<all_urls>"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "cors-unblock@rxliuli.com"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "action": {
    "default_title": "Default Popup Title",
    "default_popup": "popup.html"
  },
  "options_ui": {
    "page": "options.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "run_at": "document_start",
      "js": [
        "content-scripts/content.js"
      ]
    }
  ]
}