Examine source code of TabTime

{
  "manifest_version" : 3 ,
  "name" : "Webtime Tracker",
  "version" : "1.1.1",
  "description" : "Track time spent on websites, run multiple stopwatches and timers, plan your day, take notes and stay hydrated — all stored locally.",
  "author": "Webtime Tracker Team",
  "permissions" : [
    "tabs" ,
    "storage" ,
    "alarms" ,
    "idle" ,
    "notifications" 
  ],
  "host_permissions" : [
    "<all_urls>" 
  ],
  "background" : {
    "scripts" : [
      "background/background.js" 
    ]
  },
  "content_scripts" : [
    {
      "matches" : [
        "<all_urls>" 
      ],
      "js" : [
        "content/overlay-style.js" ,
        "content/overlay.js" 
      ]
    }
  ],
  "action" : {
    "default_popup" : "popup/popup.html",
    "default_title" : "Webtime Tracker",
    "default_icon" : {
      "48" : "icons/icon-48.png",
      "96" : "icons/icon-96.png"
    }
  },
  "commands" : {
    "_execute_action": {
      "suggested_key": {
        "default": "Alt+Shift+W"
      },
      "description" : "Open Webtime Tracker"
    }
  },
  "icons" : {
    "48" : "icons/icon-48.png",
    "96" : "icons/icon-96.png",
    "128" : "icons/icon-128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "webtime-tracker@example.com",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    },
    "gecko_android": {
      "strict_min_version": "142.0"
    }
  }
}