message: Add TraceMe for executor callbacks.
diff: @@ -2495,6 +2495,7 @@ void ExecutorState::Finish() {
  auto done_cb = std::move(done_cb_);
  auto runner = std::move(runner_);
  mu_.unlock();
  + int64 step_id = step_id_;
  CHECK(done_cb != nullptr);
  Device* device = impl_->params_.device;
  @@ -2541,7 +2542,14 @@ void ExecutorState::Finish() {
  }
  }
  delete this;
  - runner([=]() { done_cb(status); });
  + runner([=]() {
  + profiler::TraceMe traceme(
  + [&] {
  + return absl::StrCat("ExecutorDoneCallback#id=", step_id, "#");
  + },
  + 2);
  + done_cb(status);
  + });
  return;
  }
  @@ -2553,11 +2561,25 @@ void ExecutorState::Finish() {
  device->Sync([=](Status new_status) mutable {
  status.Update(new_status);
  delete this;
  - runner([=]() { done_cb(status); });
  + runner([=]() {
  + profiler::TraceMe traceme(
  + [&] {
  + return absl::StrCat("ExecutorDoneCallback#id=", step_id, "#");
  + },
  + 2);
  + done_cb(status);
  + });
  });
  } else {
  delete this;
  - runner([=]() { done_cb(status); });
  + runner([=]() {
  + profiler::TraceMe traceme(
  + [&] {
  + return absl::StrCat("ExecutorDoneCallback#id=", step_id, "#");
  + },
  + 2);
  + done_cb(status);
  + });
  }
  }
  