Examine source code of Focus Sound Loop

{
  "manifest_version": 2,
  "name": "Focus Sound Loop",
  "version": "1.0",
  "description": "Play gentle ambient loops (rain, café, keyboard) from the toolbar to help focus.",
  "icons": {
    "48": "icons/icon48.svg",
    "128": "icons/icon128.svg"
  },
  "browser_action": {
    "default_title": "Focus Sound Loop",
    "default_popup": "popup.html",
    "default_icon": {
      "48": "icons/icon48.svg"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "permissions": [],
  "browser_specific_settings": {
    "gecko": {
      "id": "{d949d1e1-89a9-431b-bb52-504f231d9297}"
    }
  }
}