Examine source code of Simple UA Switcher

{
  "manifest_version": 2,
  "name": "Simple UA Switcher",
  "version": "1.0.1",
  "description": "The easiest way to switch your UA / UA를 바꾸는 가장 쉬운 방법!",
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "storage",
    "activeTab",
    "<all_urls>"
  ],
  "icons": {
    "48": "icon48.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "browser_action": {
    "browser_style": true,
    "default_icon": {
      "16": "icon48.png",
      "32": "icon48.png"
    },
    "default_title": "Set User-Agent",
    "theme_icons": [
      {
        "light": "icon48.png",
        "dark": "icon48.png",
        "size": 16
      },
      {
        "light": "icon48.png",
        "dark": "icon48.png",
        "size": 32
      }
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{b0b3ba92-f778-4548-bdc3-c2e800d90b4d}"
    }
  }
}