Merge "Fix the compiler error for the ternary operator, caused by Eigen rebase."

  const auto delta_q = b.inverse() * a;

  // Check that delta_q.w() == 1, Eigen doesn't respect this convention. If

  // delta_q.w() == -1, we'll get the opposite velocity.

  return 2.0 * (delta_q.w() < 0 ? -delta_q.vec() : delta_q.vec()) / delta_time;

  return 2.0 * (delta_q.w() < 0 ? static_cast<vec3>(-delta_q.vec()) : delta_q.vec()) / delta_time;

}

Velocity Predictor::PredictVelocity(int64_t time_ns) const {