Examine source code of URL Change Trigger

{
  "manifest_version": 2,
  "name": "URL Change Trigger",
  "version": "1.0.0",
  "description": "Automatically closes or mutes a tab when its URL changes.",
  "permissions": [
    "tabs"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": "icon48.png",
    "default_popup": "popup.html",
    "default_title": "Mark Tab"
  },
  "icons": {
    "16": "icon16.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "urlchangetrigger@karel-hovorka.eu",
      "strict_min_version": "109.0"
    }
  }
}