Examine source code of [Deprecated] autoConvert - you select, it converts

{
  "manifest_version": 2,
  "version": "2018.1017.0.20resigned1",
  "version_name": "2018.1017.0.19 release",
  "name": "__MSG_appName__",
  "short_name": "__MSG_shortName__",
  "description": "__MSG_appDescription__",
  "applications": {
    "gecko": {
      "id": "autoconvert_select@net.c306"
    }
  },
  "icons": {
    "16": "img/ac16-nb.png",
    "48": "img/ac48-nb.png",
    "128": "img/ac128-nb.png"
  },
  "default_locale": "en",
  "background": {
    "scripts": [
      "js/ext/moment.min.js",
      "js/ext/moment-timezone-with-data.min.js",
      "js/constants.js",
      "js/utils.js",
      "js/currencyStore.js",
      "js/converter.js",
      "js/bg.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_icon": {
      "16": "img/ac16-nb.png",
      "24": "img/ac24-nb.png",
      "32": "img/ac32-nb.png"
    },
    "default_title": "__MSG_appNAME__",
    "default_popup": "popup.html"
  },
  "commands": {
    "_execute_browser_action": {
      "suggested_key": {
        "windows": "Ctrl+Period",
        "mac": "Command+Period",
        "chromeos": "Ctrl+Period",
        "linux": "Ctrl+Period"
      }
    }
  },
  "options_ui": {
    "page": "options.html",
    "open_in_tab": false
  },
  "minimum_chrome_version": "49",
  "offline_enabled": true,
  "permissions": [
    "alarms",
    "storage"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "css": [
        "css/acs.css"
      ]
    },
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "js/ext/jquery-3.3.1.min.js",
        "js/constants.js",
        "js/acs.js"
      ]
    }
  ]
}