Examine source code of Time Trackers

{
  "manifest_version": 2,
  "name": "Time Tracker",
  "version": "1.0",
  "description": "A simple addon to track the time spent on different websites.",
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "permissions": [
    "storage",
    "tabs",
    "activeTab"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{1db4564d-2c9f-46c8-b791-fe6d8c933a9d}"
    }
  }
}