Examine source code of TagName Extension

{
  "manifest_version": 2,
  "name": "TagName Extension",
  "version": "101",
  "description": "Encode text for TagName",
  "icons": {
    "16": "icon16.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "permissions": [
    "activeTab",
    "clipboardRead"
  ],
  "browser_action": {
    "default_icon": {
      "16": "icon16.png",
      "48": "icon48.png",
      "128": "icon128.png"
    },
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{f7d8b76a-3e09-46c8-968e-78ba938dbe5e}"
    }
  }
}