Examine source code of ProxyFire

{
  "manifest_version": 2,
  "name": "ProxyFire",
  "version": "1.5",
  "description": "Allows to proxy each container individually, aditional it adds a custom header with the container's name and color so it can be highlighted in burp",
  "icons": {
    "128": "res/icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "stripper@burp",
      "strict_min_version": "91.1.0"
    }
  },
  "permissions": [
    "activeTab",
    "contextualIdentities",
    "cookies",
    "webRequest",
    "webRequestBlocking",
    "<all_urls>",
    "proxy",
    "storage",
    "scripting"
  ],
  "browser_action": {
    "default_icon": "res/icon.png",
    "default_title": "test",
    "default_popup": "popup/main.html"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "options_ui": {
    "page": "settings/settings.html"
  }
}