message: Update signature of the LMDBDataset to match recent changes
diff: @@ -43,10 +43,10 @@ class LMDBDatasetOp : public DatasetOpKernel {
  }
  private:
  - class Dataset : public GraphDatasetBase {
  + class Dataset : public DatasetBase {
  public:
  Dataset(OpKernelContext* ctx, const std::vector<string>& filenames)
  - : GraphDatasetBase(ctx), filenames_(filenames) {}
  + : DatasetBase(DatasetContext(ctx)), filenames_(filenames) {}
  std::unique_ptr<IteratorBase> MakeIteratorInternal(
  const string& prefix) const override {
  @@ -69,7 +69,8 @@ class LMDBDatasetOp : public DatasetOpKernel {
  string DebugString() const override { return "LMDBDatasetOp::Dataset"; }
  protected:
  - Status AsGraphDefInternal(DatasetGraphDefBuilder* b,
  + Status AsGraphDefInternal(SerializationContext* ctx,
  + DatasetGraphDefBuilder* b,
  Node** output) const override {
  Node* filenames = nullptr;
  TF_RETURN_IF_ERROR(b->AddVector(filenames_, &filenames));
  