Examine source code of Toggle Referrer (with optional spoofing feature)

{
  "manifest_version": 2,
  "name": "Toggle Referrer",
  "version": "5.14.0",
  "description": "__MSG_extensionDescription__",
  "browser_specific_settings": {
    "gecko": {
      "id": "{8883111b-4bc8-4a99-b37f-5672f6cf9597}",
      "strict_min_version": "60.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "icons": {
    "24": "icons/togglereferrer.svg",
    "32": "icons/togglereferrer.svg",
    "50": "icons/togglereferrer.svg"
  },
  "background": {
    "scripts": [
      "utils/iconupdater.js",
      "background.js",
      "spoofing.js"
    ]
  },
  "browser_action": {
    "browser_style": true,
    "default_icon": "icons/togglereferrer.svg",
    "theme_icons": [
      {
        "dark": "icons/togglereferrer.svg",
        "light": "icons/togglereferrer-light.svg",
        "size": 19
      }
    ]
  },
  "options_ui": {
    "page": "options.html",
    "browser_style": true,
    "open_in_tab": false
  },
  "commands": {
    "_execute_browser_action": {}
  },
  "permissions": [
    "privacy",
    "storage"
  ],
  "optional_permissions": [
    "webRequest",
    "webRequestBlocking",
    "<all_urls>"
  ],
  "default_locale": "en"
}