Examine source code of UA Header Spoofer v2

{
  "manifest_version": 2,
  "name": "UA Header Spoofer v2",
  "version": "1.2.5",
  "description": "UA Header Spoofer v2",
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "storage",
    "tabs",
    "activeTab",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_title": "UA Spoofer"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "testtfkk@dolanesia.com",
      "strict_min_version": "142.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "optional": []
      }
    }
  }
}