Moves the state of that into this LogStreamer.
that
LogStreamer
Declared in <absl/log/log_streamer.h>
<absl/log/log_streamer.h>
LogStreamer(LogStreamer&& that) noexcept;
A moved-from absl::LogStreamer does not LOG when destroyed, and a program that streams into one has undefined behavior.
absl::LogStreamer
LOG