PVS-Studio warning V530 for Chromium

bool NpProxyService::GetProxyValueJSONString(std::string* output)
{
  DCHECK(output);
  output->empty();
  ...
}

This is what should have been written here: output->clear();

This suspicious code was found in Chromium project by PVS-Studio static code analyzer.
Warning message is:
V530 The return value of function 'empty' is required to be utilized.  chrome_frame_npapi  np_proxy_service.cc  293

PVS-Studio is a static analyzer for detecting bugs in the source code of applications written in C, C++, C++11, C++/CX. Site: http://www.viva64.com/en/pvs-studio/