Examine source code of YouTube/Twitch Bookmarker

{
  "manifest_version": 2,
  "name": "YouTube/Twitch Bookmarker",
  "version": "1.2.4",
  "description": "Bookmark youtube or twitch video with current time on current tab in Bookmark Toolbar",
  "icons": {
    "48": "icons/icon-48.png"
  },
  "browser_action": {
    "default_icon": {
      "19": "icons/icon-19.png",
      "38": "icons/icon-38.png"
    }
  },
  "permissions": [
    "bookmarks",
    "tabs",
    "activeTab"
  ],
  "background": {
    "scripts": [
      "main.js"
    ]
  },
  "applications": {
    "gecko": {
      "id": "{669c77c0-1c4a-4eab-b9d8-6be137fc64db}"
    }
  }
}