Examine source code of Music Player Extension

{
  "manifest_version": 2,
  "name": "Music Player Extension",
  "version": "1.0",
  "description": "Play trending and international music when a tab is closed",
  "permissions": [
    "activeTab",
    "storage",
    "tabs"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "48": "icons/icon.png",
      "96": "icons/icon@2x.png"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "applications": {
    "gecko": {
      "id": "musicplayer@customaddon",
      "strict_min_version": "60.0"
    }
  }
}