Examine source code of Modifier User-Agent

{
  "manifest_version": 2,
  "name": "Modifier User-Agent",
  "version": "1.0",
  "description": "Changer le User-Agent du navigateur",
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "<all_urls>",
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{625aed4f-aaaa-44a1-adc7-ec10f70a307a}"
    }
  }
}