Examine source code of recs2spotify

{
  "name": "recs2spotify",
  "description": "Simple extension that exports selected thread music recommendations from music recs without context facebook group",
  "version": "0.2.3",
  "permissions": [
    "tabs",
    "identity",
    "storage",
    "activeTab"
  ],
  "content_scripts": [
    {
      "js": [
        "core.js"
      ],
      "matches": [
        "https://www.facebook.com/groups/1664811250303043",
        "https://www.facebook.com/groups/1664811250303043/*",
        "https://www.facebook.com/groups/1664811250303043/**/*"
      ]
    }
  ],
  "page_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icons/icon16.png",
      "48": "icons/icon48.png",
      "128": "icons/icon128.png"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "manifest_version": 2
}