Method rbegin

be/src/gutil/strings/stringpiece.h:268–270

  iterator begin() const { return ptr_; }
  iterator end() const { return ptr_ + length_; }
  const_reverse_iterator rbegin() const {
    return const_reverse_iterator(ptr_ + length_);
  }
  const_reverse_iterator rend() const {
    return const_reverse_iterator(ptr_);
  }