Examine source code of Focus Time

{
  "manifest_version": 2,
  "name": "Focus Timer",
  "version": "1.0",
  "description": "A simple focus timer with breaks to help you stay productive.",
  "background": {
    "scripts": [
      "popup.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "permissions": [
    "activeTab"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{6b22470a-df6c-4da9-8fa4-b23f02634fb5}"
    }
  }
}