Examine source code of watch-your-time

{
  "manifest_version": 2,
  "name": "watch-your-time",
  "version": "1.0",
  "description": "A simple, privacy-focused Firefox add-on that tracks time spent on websites. No external servers, no tracking, no analytics!",
  "permissions": [
    "storage",
    "tabs",
    "activeTab"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_start"
    }
  ],
  "browser_action": {
    "default_icon": "icons/icon.png",
    "default_popup": "popup.html",
    "default_title": "Watch Your Time"
  },
  "icons": {
    "16": "icons/icon16.png",
    "24": "icons/icon24.png",
    "48": "icons/icon48.png",
    "1000": "icons/icon.png"
  },
  "web_accessible_resources": [
    "icons/icon48.png"
  ],
  "applications": {
    "gecko": {
      "id": "watch-your-time@ps428.com"
    }
  }
}