Examine source code of Live Dev

{
  "manifest_version": 2,
  "name": "Live Dev",
  "version": "1.0",
  "description": "Automatically reload client-side assets without refreshing the page.",
  "icons": {
    "48": "icon.svg"
  },
  "permissions": [
    "activeTab",
    "tabs"
  ],
  "page_action": {
    "default_icon": "icon.svg",
    "default_title": "Live Dev",
    "show_matches": [
      "<all_urls>"
    ]
  },
  "background": {
    "scripts": [
      "main.js"
    ]
  }
}