message: Use workgroup-local reductions for MeanStdDevNormalization.
diff: @@ -30,6 +30,9 @@ class MeanStdDevNormalization : public GPUOperation {
  public:
  explicit MeanStdDevNormalization(const OperationDef& definition);
  + absl::Status Tune(const TuningParameters& params) override {
  + return absl::OkStatus();
  + }
  int3 GetGridSize() const override;
  // Move only
  