Examine source code of Grassboy Clipboard

{
  "manifest_version": 2,
  "name": "Grassboy Clipboard",
  "author": "小胖子．草兒 Grassboy @plurk.com/xuite.net",
  "description": "提供一個函數可以存取系統的剪貼簿\n gClipboard 使用方式： gClipboard([function]): 取得系統剪貼簿的內容(會有確認訊息)，並傳回至 callback function;\n gClipboard([string/number/object]): 將 [string/number/object] 複製至系統剪貼簿(會有確認訊息)\n\n授權方式: MIT License\nAddon Icon Credit: Deleket (Jojo Mendoza)",
  "version": "0.57.2resigned1",
  "homepage_url": "https://github.com/Grassboy/gClipboard57/",
  "icons": {
    "48": "icons/icon48.png",
    "64": "icons/icon64.png"
  },
  "permissions": [
    "<all_urls>",
    "clipboardWrite",
    "clipboardRead"
  ],
  "applications": {
    "gecko": {
      "id": "jid1-waViH92bZ6IdCA@jetpack"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "main.js"
      ]
    }
  ]
}