Examine source code of Knife Hit HTML5 Fun

{
  "manifest_version": 2,
  "name": "Knife Hit HTML5 Game",
  "version": "1.0",
  "description": "Knife Hit HTML5 Game is extension Throw knives carefully at the spinning targets.",
  "permissions": [],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "128": "images/kife-logo.png"
    }
  },
  "icons": {
    "128": "images/kife-logo.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{9861c6ed-36b4-4e85-a5ba-e4d8b646a517}"
    }
  }
}