Examine source code of Simple Stopwatch Basic

{
  "manifest_version": 2,
  "name": "Simple Stopwatch",
  "version": "1.0",
  "description": "Simple Stopwatch is a useful widget. This widget works as a simple stopwatch that you can use from the widget popup.",
  "permissions": [],
  "browser_action": {
    "default_popup": "game.html",
    "default_icon": {
      "128": "images/watch-logo.png"
    }
  },
  "icons": {
    "128": "images/watch-logo.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{2e137d48-0dab-4d33-8bd2-40b7f7a2f502}"
    }
  }
}