Examine source code of Tag It

{
  "manifest_version": 2,
  "name": "Tag It",
  "version": "1.0",
  "description": "Add custom tags next to usernames on YCombinator to remember context or associations.",
  "icons": {
    "48": "icon.png"
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "permissions": [
    "storage",
    "activeTab"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{0107c4ac-d4c7-4689-a604-dccd05c3e5e6}"
    }
  }
}