  inline int FlatSize() const {
    int buffer_size = 1;
    const int* dims_data = reinterpret_cast<const int*>(DimsData());
    for (int i = 0; i < size_; i++) {
      buffer_size *= dims_data[i];
    }
    return buffer_size;
  }
  inline int FlatSize() const {
    int buffer_size = 1;
    const int* dims_data = reinterpret_cast<const int*>(DimsData());
    for (int i = 0; i < size_; i++) {
      buffer_size *= dims_data[i];
    }
    return buffer_size;
  }