message: Allow BF16 to use error spec.
diff: @@ -387,6 +387,7 @@ void ClientLibraryTestBase::ComputeAndCompareR1(
  tensorflow::gtl::ArraySlice<GlobalData*> arguments, ErrorSpec error) {
  static_assert(std::is_same<NativeT, float>::value ||
  std::is_same<NativeT, double>::value ||
  + std::is_same<NativeT, bfloat16>::value ||
  std::is_same<NativeT, complex64>::value,
  "Float or complex type required when specifying an ErrorSpec");
  std::unique_ptr<Literal> expected_literal =
  @@ -411,6 +412,7 @@ void ClientLibraryTestBase::ComputeAndCompareR2(
  tensorflow::gtl::ArraySlice<GlobalData*> arguments, ErrorSpec error) {
  static_assert(std::is_same<NativeT, float>::value ||
  std::is_same<NativeT, double>::value ||
  + std::is_same<NativeT, bfloat16>::value ||
  std::is_same<NativeT, complex64>::value,
  "Float or complex type required when specifying an ErrorSpec");
  std::unique_ptr<Literal> expected_literal =
  @@ -435,6 +437,7 @@ void ClientLibraryTestBase::ComputeAndCompareR3(
  tensorflow::gtl::ArraySlice<GlobalData*> arguments, ErrorSpec error) {
  static_assert(std::is_same<NativeT, float>::value ||
  std::is_same<NativeT, double>::value ||
  + std::is_same<NativeT, bfloat16>::value ||
  std::is_same<NativeT, complex64>::value,
  "Float or complex type required when specifying an ErrorSpec");
  std::unique_ptr<Literal> expected_literal =
  @@ -459,6 +462,7 @@ void ClientLibraryTestBase::ComputeAndCompareR4(
  tensorflow::gtl::ArraySlice<GlobalData*> arguments, ErrorSpec error) {
  static_assert(std::is_same<NativeT, float>::value ||
  std::is_same<NativeT, double>::value ||
  + std::is_same<NativeT, bfloat16>::value ||
  std::is_same<NativeT, complex64>::value,
  "Float or complex type required when specifying an ErrorSpec");
  std::unique_ptr<Literal> expected_literal =
  