Fix check_backward_test.cc to use new DeviceId
Fix check_backward_test.cc to use new DeviceId

ktnyt/chainer,hvy/chainer,ktnyt/chainer,keisuke-umezawa/chainer,jnishi/chainer,okuta/chainer,keisuke-umezawa/chainer,niboshi/chainer,niboshi/chainer,jnishi/chainer,wkentaro/chainer,pfnet/chainer,chainer/chainer,chainer/chainer,chainer/chainer,okuta/chainer,okuta/chainer,ktnyt/chainer,wkentaro/chainer,hvy/chainer,hvy/chainer,chainer/chainer,okuta/chainer,niboshi/chainer,keisuke-umezawa/chainer,tkerola/chainer,hvy/chainer,niboshi/chainer,jnishi/chainer,wkentaro/chainer,wkentaro/chainer,ktnyt/chainer,jnishi/chainer,keisuke-umezawa/chainer