message: Use TF_CHECK_OK() to check:
  1. perm_node->attr();
  2. AddEdge().
diff: @@ -1025,8 +1025,7 @@ class MklLayoutRewritePass : public GraphOptimizationPass {
  e->dst_input() == kPermTensorIndex) {
  // we find the "perm" node, now try to retrieve its value.
  const TensorProto* proto = nullptr;
  - bool perm_has_value_attr = GetNodeAttr(perm_node->def(), "value", &proto).ok();
  - DCHECK(perm_has_value_attr);
  + TF_CHECK_OK(GetNodeAttr(perm_node->def(), "value", &proto));
  DataType type;
  GetNodeAttr(perm_node->def(), "dtype", &type);
  @@ -3111,9 +3110,9 @@ Status MklLayoutRewritePass::FuseTransposeMklOpTranspose(
  for (const Edge* e : transpose_to_nchw->out_edges()) {
  if (!e->IsControlEdge()) {
  const int kTransposeWithMklOpOutputSlot = 0;
  - bool succ_add_edge = (*g)->AddEdge(new_node, kTransposeWithMklOpOutputSlot, e->dst(),
  + auto new_edge = (*g)->AddEdge(new_node, kTransposeWithMklOpOutputSlot, e->dst(),
  e->dst_input());
  - DCHECK(succ_add_edge);
  + DCHECK(new_edge);
  }
  }
  