message: Initialize the tag producer so we get some tag extraction happening and counted toward
  the memory usage in the unit test.
diff: #include "common/common/c_smart_ptr.h"
  #include "common/memory/stats.h"
  #include "common/stats/stats_matcher_impl.h"
  +#include "common/stats/tag_producer_impl.h"
  #include "common/stats/thread_local_store.h"
  #include "test/common/stats/stat_test_utility.h"
  @@ -650,6 +651,10 @@ TEST_F(HeapStatsThreadLocalStoreTest, MemoryWithoutTls) {
  return;
  }
  + // Use a tag producer that will produce tags.
  + envoy::config::metrics::v2::StatsConfig stats_config;
  + store_->setTagProducer(std::make_unique<TagProducerImpl>(stats_config));
  +
  const size_t million = 1000 * 1000;
  const size_t start_mem = Memory::Stats::totalCurrentlyAllocated();
  if (start_mem == 0) {
  @@ -660,7 +665,7 @@ TEST_F(HeapStatsThreadLocalStoreTest, MemoryWithoutTls) {
  1000, [this](absl::string_view name) { store_->counter(std::string(name)); });
  const size_t end_mem = Memory::Stats::totalCurrentlyAllocated();
  EXPECT_LT(start_mem, end_mem);
  - EXPECT_LT(end_mem - start_mem, 22 * million); // actual value: 21190128 as of Oct 26, 2018
  + EXPECT_LT(end_mem - start_mem, 28 * million); // actual value: 27203216 as of Oct 29, 2018
  }
  TEST_F(HeapStatsThreadLocalStoreTest, MemoryWithTls) {
  @@ -668,6 +673,10 @@ TEST_F(HeapStatsThreadLocalStoreTest, MemoryWithTls) {
  return;
  }
  + // Use a tag producer that will produce tags.
  + envoy::config::metrics::v2::StatsConfig stats_config;
  + store_->setTagProducer(std::make_unique<TagProducerImpl>(stats_config));
  +
  const size_t million = 1000 * 1000;
  store_->initializeThreading(main_thread_dispatcher_, tls_);
  const size_t start_mem = Memory::Stats::totalCurrentlyAllocated();
  @@ -679,7 +688,7 @@ TEST_F(HeapStatsThreadLocalStoreTest, MemoryWithTls) {
  1000, [this](absl::string_view name) { store_->counter(std::string(name)); });
  const size_t end_mem = Memory::Stats::totalCurrentlyAllocated();
  EXPECT_LT(start_mem, end_mem);
  - EXPECT_LT(end_mem - start_mem, 25 * million); // actual value: 24469488 as of Oct 26, 2018
  + EXPECT_LT(end_mem - start_mem, 31 * million); // actual value: 30482576 as of Oct 29, 2018
  }
  TEST_F(StatsThreadLocalStoreTest, ShuttingDown) {
  