message: give each line in cupti plane a default name, in case traceme is not captured anything on this thread. this should not happen in normal cases.
  we don't want to get thread name at each callback.
diff: @@ -247,9 +247,8 @@ class CuptiTraceCollectorImpl : public CuptiTraceCollector {
  // start_walltime_ns to normalize with CPU wall time.
  static void NormalizeTimeStamps(XPlaneBuilder* plane,
  uint64 start_walltime_ns) {
  - plane->ForEachLine([&](tensorflow::profiler::XLineBuilder line) {
  - line.SetTimestampNs(start_walltime_ns);
  - });
  + plane->ForEachLine(
  + [&](XLineBuilder line) { line.SetTimestampNs(start_walltime_ns); });
  }
  struct CorrelationInfo {
  @@ -418,10 +417,13 @@ class CuptiTraceCollectorImpl : public CuptiTraceCollector {
  CreateXEvent(event, plane, start_gpu_ns, end_gpu_ns, &line);
  events_types_per_line[line_id].emplace(event.type);
  }
  - device_plane->ForEachLine([&](tensorflow::profiler::XLineBuilder line) {
  + device_plane->ForEachLine([&](XLineBuilder line) {
  line.SetName(
  GetDeviceXLineName(line.Id(), events_types_per_line[line.Id()]));
  });
  + host_plane->ForEachLine([&](XLineBuilder line) {
  + line.SetName(absl::StrCat("Host Threads/", line.Id()));
  + });
  events.clear();
  }
  