message: Estimate IdentityN as Identity.
diff: @@ -35,6 +35,7 @@ constexpr char kMatMul[] = "MatMul";
  constexpr char kSparseMatMul[] = "SparseMatMul";
  constexpr char kPlaceholder[] = "Placeholder";
  constexpr char kIdentity[] = "Identity";
  +constexpr char kIdentityN[] = "IdentityN";
  constexpr char kRefIdentity[] = "RefIdentity";
  constexpr char kNoOp[] = "NoOp";
  constexpr char kReshape[] = "Reshape";
  @@ -211,6 +212,7 @@ OpLevelCostEstimator::OpLevelCostEstimator() {
  {kPlaceholder, wrap(&OpLevelCostEstimator::PredictIdentity)},
  {kIdentity, wrap(&OpLevelCostEstimator::PredictIdentity)},
  + {kIdentityN, wrap(&OpLevelCostEstimator::PredictIdentity)},
  {kRefIdentity, wrap(&OpLevelCostEstimator::PredictIdentity)},
  {kStopGradient, wrap(&OpLevelCostEstimator::PredictIdentity)},
  {kPreventGradient, wrap(&OpLevelCostEstimator::PredictIdentity)},
  