AudioRendererMixerManager* RenderThreadImpl::GetAudioRendererMixerManager() {
  if (!audio_renderer_mixer_manager_) {
    audio_renderer_mixer_manager_.reset(new AudioRendererMixerManager(
        GetAudioHardwareConfig()));
  }

  return audio_renderer_mixer_manager_.get();
}

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.