Examine source code of Tenhou score pane

{
  "manifest_version": 2,
  "name": "Tenhou score pane",
  "version": "2.1.0",
  "description": "Adds a pane to the tenhou.net and ron2.jp clients (/3, /4) in-game which contains the score history of the hands in the current game",
  "icons": {
    "16": "icons/16.png",
    "32": "icons/32.png",
    "48": "icons/48.png",
    "128": "icons/128.png"
  },
  "permissions": [
    "storage"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://tenhou.net/0*",
        "*://tenhou.net/4*",
        "*://tenhou.net/3*",
        "*://ron2.jp/3*"
      ],
      "js": [
        "jquery.js",
        "chart.js",
        "content.js"
      ],
      "css": [
        "content.css"
      ],
      "run_at": "document_idle"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{bdc6ddd4-1fb7-4846-b11b-21e40fa85f8b}"
    }
  }
}