PVS-Studio warning V510 for Chromium

typedef std::wstring string16;

const base::string16& relaunch_flags() const {
  return relaunch_flags_;
}

int RelaunchChrome(const DelegateExecuteOperation& operation)
{
  AtlTrace("Relaunching [%ls] with flags [%s]\n",
           operation.mutex().c_str(),
           operation.relaunch_flags());     <<<<====
  ....
}

This suspicious code was found in Chromium project by PVS-Studio static code analyzer.
Warning message is:
V510 The 'AtlTrace' function is not expected to receive class-type variable as third actual argument. delegate_execute.cc 96

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/