Examine source code of User Agent Editor

{
  "manifest_version": 2,
  "background": {
    "page": "background.html"
  },
  "options_ui": {
    "page": "options.html",
    "browser_style": false,
    "open_in_tab": false
  },
  "name": "User-Agent Editor",
  "short_name": "User-Agent Editor",
  "description": "User-Agent Editor is a quick and easy way to switch between user-agents.",
  "version": "2.0",
  "browser_action": {
    "default_icon": {
      "19": "img/icon19.png",
      "38": "img/icon38.png"
    },
    "default_popup": "popup.html",
    "default_title": "User-Agent Editor"
  },
  "icons": {
    "16": "img/icon16.png",
    "48": "img/icon48.png",
    "128": "img/icon128.png"
  },
  "applications": {
    "gecko": {
      "id": "@uaswitcher",
      "strict_min_version": "57.0"
    }
  },
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "tabs",
    "http://*/",
    "https://*/",
    "contextMenus"
  ],
  "content_scripts": [
    {
      "js": [
        "js/content.js"
      ],
      "matches": [
        "*://*/*"
      ],
      "run_at": "document_start"
    }
  ]
}