message: respect device_trace_level option.
diff: @@ -196,6 +196,7 @@ Status GpuTracer::CollectData(RunMetadata* run_metadata) {
  }
  Status GpuTracer::CollectData(XSpace* space) {
  + VLOG(2) << "Collecting data to XSpace from GpuTracer.";
  switch (profiling_state_) {
  case State::kNotStarted:
  VLOG(1) << "No trace data collected, session wasn't started";
  @@ -230,7 +231,7 @@ Status GpuTracer::CollectData(XSpace* space) {
  // Not in anonymous namespace for testing purposes.
  std::unique_ptr<profiler::ProfilerInterface> CreateGpuTracer(
  const ProfileOptions& options) {
  - VLOG(2) << "Collecting data to XSpace from GpuTracer.";
  + if (options.device_tracer_level() == 0) return nullptr;
  if (options.device_type() != ProfileOptions::GPU &&
  options.device_type() != ProfileOptions::UNSPECIFIED)
  return nullptr;
  