Examine source code of GitHub user notes

{
  "manifest_version": 2,
  "name": "ff_plugin_github_user_notes",
  "version": "1.3",
  "browser_specific_settings": {
    "gecko": {
      "id": "ff_plugin_github_user_notes@zxkmm.com"
    }
  },
  "description": "Make notes regarding specific GitHub users",
  "permissions": [
    "activeTab",
    "storage"
  ],
  "icons": {
    "48": "icons/icon48.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://github.com/*"
      ],
      "js": [
        "user_notes.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "event_handler.js"
    ],
    "persistent": false
  }
}