Examine source code of Animated Page Action plus

{
  "name": "Animated Page Action",
  "description": "This extension adds an animated browser action to the toolbar.",
  "version": "1.2",
  "background": {
    "page": "background.html"
  },
  "page_action": {
    "default_title": "First icon"
  },
  "manifest_version": 2,
  "browser_specific_settings": {
    "gecko": {
      "id": "{0c354de9-8a5c-4a9c-b7a4-595fa19b26a3}"
    }
  }
}