message: [XLA:GPU][NFC] Use absl::flat_hash_map instead of std::map.
diff: @@ -163,7 +163,8 @@ Status GpuExecutable::ExecuteThunks(
  [&] { return absl::StrCat(module_name_, ":XLA GPU module"); },
  tensorflow::profiler::TraceMeLevel::kInfo);
  - std::map<const Thunk*, std::unique_ptr<se::Event>> thunk_to_finish_event;
  + absl::flat_hash_map<const Thunk*, std::unique_ptr<se::Event>>
  + thunk_to_finish_event;
  std::vector<std::function<void()>> deferred_host_callbacks;
  for (const std::unique_ptr<Thunk>& thunk : thunk_schedule_->TotalOrder()) {
  // Annotate execution of this op if tracing was enabled when we started
  