message: Switch to new way of allocating string tensors
diff: @@ -28,13 +28,13 @@ constexpr char kDataFileLoc[] = "core/lib/lmdb/testdata";
  class LMDBDatasetParams : public DatasetParams {
  public:
  - LMDBDatasetParams(std::vector<std::string> filenames,
  + LMDBDatasetParams(std::vector<tstring> filenames,
  DataTypeVector output_dtypes,
  std::vector<PartialTensorShape> output_shapes,
  string node_name)
  : DatasetParams(std::move(output_dtypes), std::move(output_shapes),
  std::move(kNodeName)),
  - filenames_(CreateTensor<std::string>(
  + filenames_(CreateTensor<tstring>(
  TensorShape({static_cast<int>(filenames.size())}), filenames)) {}
  virtual std::vector<Tensor> GetInputTensors() const override {
  @@ -69,10 +69,10 @@ class LMDBDatasetOpTest : public DatasetOpsTestBase {};
  // directory, and return the full path to the copied file.
  // This copying is necessary because LMDB creates lock files adjacent
  // to files that it reads.
  -string MaybeCopyDataFile() {
  - string src_loc =
  +tstring MaybeCopyDataFile() {
  + tstring src_loc =
  io::JoinPath(testing::TensorFlowSrcRoot(), kDataFileLoc, kDataFileName);
  - string dest_loc = io::JoinPath(testing::TmpDir(), kDataFileName);
  + tstring dest_loc = io::JoinPath(testing::TmpDir(), kDataFileName);
  FileSystem* fs; // Pointer to singleton
  TF_EXPECT_OK(Env::Default()->GetFileSystemForFile(src_loc, &fs));
  @@ -128,7 +128,7 @@ LMDBDatasetParams InvalidPathInMiddle() {
  }
  // The tensors we expect to see each time we read through the input data file.
  -const std::vector<Tensor> kFileOutput = CreateTensors<string>(
  +const std::vector<Tensor> kFileOutput = CreateTensors<tstring>(
  TensorShape({}),
  {
  // Each call to GetNext() produces two scalar string tensors, but the
  