blink::WebString RenderFrameImpl::userAgentOverride(blink::WebLocalFrame* frame,
                                                    const blink::WebURL& url) {
  DCHECK(!frame_ || frame_ == frame);
  if (!render_view_->webview() || !render_view_->webview()->mainFrame() ||
      render_view_->renderer_preferences_.user_agent_override.empty()) {
    return blink::WebString();
  }

  WebFrame* main_frame = render_view_->webview()->mainFrame();
  WebDataSource* data_source = NULL;
  if (main_frame->provisionalDataSource())
    data_source = main_frame->provisionalDataSource();
  else
    data_source = main_frame->dataSource();

  InternalDocumentStateData* internal_data = data_source ?
      InternalDocumentStateData::FromDataSource(data_source) : NULL;
  if (internal_data && internal_data->is_overriding_user_agent())
    return WebString::fromUTF8(
        render_view_->renderer_preferences_.user_agent_override);
  return blink::WebString();
}

This vulnerability category highlights issues in resource management where failures to properly release memory, file handles, or other resources can degrade system performance or enable denial-of-service conditions.