Examine source code of Clear Tabs

{
  "manifest_version": 2,
  "name": "Clear Tabs",
  "version": "1.0",
  "description": "Closes all tabs",
  "icons": {
    "48": "icons/icon-48.png"
  },
  "permissions": [
    "tabs"
  ],
  "commands": {
    "_execute_browser_action": {
      "suggested_key": {
        "default": "Ctrl+Shift+L"
      }
    }
  },
  "browser_action": {
    "default_icon": "icons/icon-48.png",
    "default_title": "Clear Tabs",
    "default_popup": "popup/clear_tabs.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{26de18a5-d479-4323-8013-e031099b19d8}"
    }
  }
}