Examine source code of Daily Kanji

{
  "manifest_version": 2,
  "name": "Daily Kanji",
  "version": "1.0",
  "description": "Display a new Kanji character every day in a popup.",
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "permissions": [],
  "browser_specific_settings": {
    "gecko": {
      "id": "{d4aeb1be-1e48-49d8-9cb6-e504c4897feb}"
    }
  }
}