Examine source code of Floating Timer

{
  "manifest_version": 2,
  "name": "Floating Timer",
  "description": "Toggle a floating countdown timer with a keyboard shortcut.",
  "version": "1.0.1",
  "icons": {
    "16": "icon-16.png",
    "32": "icon-32.png",
    "48": "icon-48.png",
    "128": "icon-128.png"
  },
  "permissions": [
    "storage",
    "scripting",
    "activeTab",
    "webNavigation"
  ],
  "commands": {
    "toggle-timer": {
      "suggested_key": {
        "default": "Ctrl+Shift+Period",
        "mac": "Ctrl+Shift+Period"
      },
      "description": "Show or hide the floating timer"
    }
  },
  "web_accessible_resources": [
    "overlay.html",
    "assets/*",
    "chunks/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "floating-timer@cteerakit.github.io",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_title": "Floating Timer",
    "default_popup": "popup.html"
  }
}