Minor refactoring: removed unused parameter
Minor refactoring: removed unused parameter

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