Examine source code of Vimeo Captions

{
  "manifest_version": 2,
  "name": "Vimeo Captions",
  "version": "1.0",
  "description": "A simple tool to add, edit, and view community-generated captions for Vimeo videos.",
  "icons": {
    "48": "icon.png"
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "permissions": [],
  "applications": {
    "gecko": {
      "id": "vimeo_caption_assistant@example.com"
    }
  }
}