message: Improve debuggability of XLine/XPlane by allowing name to be printed while building.
diff: @@ -226,6 +226,7 @@ class XLineBuilder {
  int64 NumEvents() const { return line_->events_size(); }
  + absl::string_view Name() const { return line_->name(); }
  void SetName(absl::string_view name) { line_->set_name(std::string(name)); }
  void SetNameIfEmpty(absl::string_view name) {
  @@ -271,6 +272,7 @@ class XPlaneBuilder : public XStatsBuilder<XPlane> {
  int64 Id() const { return plane_->id(); }
  void SetId(int64 id) { plane_->set_id(id); }
  + absl::string_view Name() const { return plane_->name(); }
  void SetName(absl::string_view name) { plane_->set_name(std::string(name)); }
  void ReserveLines(size_t num_lines) {
  