Examine source code of Domain Switcher

{
  "name": "Domain Switcher",
  "description": "Easily switch domains between development, staging, production or other environments of projects.",
  "version": "1.1.4",
  "manifest_version": 2,
  "icons": {
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "page_action": {
    "default_icon": {
      "16": "icons/icon-16.png",
      "24": "icons/icon-24.png",
      "32": "icons/icon-32.png"
    },
    "default_title": "Domain Switcher",
    "default_popup": "popup/popup.html",
    "show_matches": [
      "http://*/*",
      "https://*/*"
    ]
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "options_ui": {
    "page": "options/options.html"
  },
  "permissions": [
    "tabs",
    "downloads"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{9df79fdf-3286-4b1f-8345-403a6e6f1a0b}"
    }
  }
}