Examine source code of Bookmark Manager Plus

{
  "manifest_version": 2,
  "name": "Bookmark Manager Plus",
  "version": "3.0",
  "description": "A modern bookmark manager",
  "permissions": [
    "bookmarks",
    "tabs",
    "storage"
  ],
  "browser_action": {
    "default_popup": "popup.html"
  },
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{69ae5d28-477a-4440-a17f-64acb4744f45}"
    }
  }
}