Examine source code of CopyHash

{
  "manifest_version": 2,
  "name": "CopyHash",
  "version": "0.1",
  "description": "Context menu button to copy md5 hash from a 4chan thumbnail to the clipboard",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "menus",
    "clipboardWrite",
    "activeTab"
  ],
  "icons": {
    "16": "ferongr-16.png"
  }
}