message: Fixed a build error due to -Wc++11-narrowing.
diff: @@ -199,11 +199,9 @@ TEST_F(HorizontalFusionTest, GradientDescentOptimizerLike) {
  HloComputation::Builder builder(TestName());
  std::vector<HloInstruction*> var_outs;
  - int64 dim = 1;
  - for (size_t i = 0; i < 128; ++i) {
  + for (int64 i = 0; i < 128; ++i) {
  // For shapes {1, 1024}, {2, 1024}, ..., {128, 1024}
  auto shape = ShapeUtil::MakeShape(F32, {i + 1, 1024});
  - dim *= 2;
  HloInstruction* param_var_in = builder.AddInstruction(
  HloInstruction::CreateParameter(i * 3 + 0, shape, "var.in"));
  HloInstruction* param_alpha =
  @@ -291,7 +289,7 @@ TEST_F(HorizontalFusionTest, RMSPropLike) {
  HloComputation::Builder builder(TestName());
  std::vector<HloInstruction*> all_outputs;
  - for (size_t i = 0; i < 48; ++i) {
  + for (int64 i = 0; i < 48; ++i) {
  auto shape = ShapeUtil::MakeShape(F32, {2, 1024 + i});
  // ms <- grad**2 (1 - rho) + ms * rho
  HloInstruction* grad = builder.AddInstruction(
  