Examine source code of User Tagger for Forums

{
  "manifest_version": 2,
  "name": "User Tagger for Forums",
  "version": "1.0",
  "description": "Add custom tags next to usernames on YCombinator to remember context or associations.",
  "permissions": [
    "activeTab",
    "storage"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://news.ycombinator.com/*"
      ],
      "js": [
        "popup.js"
      ],
      "css": [
        "popup.css"
      ],
      "run_at": "document_idle"
    }
  ],
  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "popup.html",
    "default_title": "Add User Tags"
  },
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{9f14f8b4-3c45-4109-a96e-a09f4b50d550}"
    }
  }
}