message: Reorder auto mixed precision grappler pass
  to take advantage of other optimizations
diff: @@ -174,10 +174,6 @@ Status MetaOptimizer::InitializeOptimizers(
  if (!cfg_.disable_model_pruning()) {
  optimizers->push_back(MakeUnique<ModelPruner>());
  }
  - if (AutoMixedPrecisionEnabled(cfg_.auto_mixed_precision())) {
  - optimizers->push_back(
  - MakeUnique<AutoMixedPrecision>(cfg_.auto_mixed_precision()));
  - }
  if (cfg_.implementation_selector() != RewriterConfig::OFF) {
  optimizers->push_back(MakeUnique<ImplementationSelector>());
  }
  @@ -216,6 +212,10 @@ Status MetaOptimizer::InitializeOptimizers(
  if (cfg_.layout_optimizer() != RewriterConfig::OFF) {
  optimizers->push_back(MakeUnique<LayoutOptimizer>());
  }
  + if (AutoMixedPrecisionEnabled(cfg_.auto_mixed_precision())) {
  + optimizers->push_back(
  + MakeUnique<AutoMixedPrecision>(cfg_.auto_mixed_precision()));
  + }
  if (cfg_.memory_optimization() != RewriterConfig::NO_MEM_OPT) {
  if (cfg_.memory_optimizer_target_node_name_scope().empty()) {
  optimizers->push_back(
  