Examine source code of RGL Profile Link Appender

{
  "manifest_version": 2,
  "name": "RGL Profile Link Appender",
  "version": "1.0",
  "description": "Appends a link to the player's RGL page on their Steam profile.",
  "permissions": [
    "activeTab",
    "webNavigation",
    "storage"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://steamcommunity.com/id/*",
        "*://steamcommunity.com/profiles/*"
      ],
      "js": [
        "contentScript.js"
      ]
    }
  ],
  "icons": {
    "16": "icons/16.png",
    "48": "icons/48.png",
    "128": "icons/128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{fb06be01-114d-4f1f-a3fa-24b129e27b43}"
    }
  }
}