[memory-infra] Make MemoryDumpScheduler non-thread safe singleton

base/trace_event/memory_dump_scheduler_unittest.cc

Index: base/trace_event/memory_dump_scheduler_unittest.cc
diff --git a/base/trace_event/memory_dump_scheduler_unittest.cc b/base/trace_event/memory_dump_scheduler_unittest.cc
index 05344d5e1f2d8b8c0ffa9840391bcac7f845d370..04869c497c2db8f9103a93ee6b7bbf5fb41954fe 100644
--- a/base/trace_event/memory_dump_scheduler_unittest.cc
+++ b/base/trace_event/memory_dump_scheduler_unittest.cc
@@ -24,18 +24,18 @@ class MemoryDumpSchedulerPollingTest : public testing::Test {
   void SetUp() override {
     MemoryDumpScheduler::SetPollingIntervalForTesting(1);
     uint32_t kMinPollsToDump = 5;
-    mds_.reset(new MemoryDumpScheduler(nullptr, nullptr));
+    mds_ = MemoryDumpScheduler::GetInstance();
+    mds_->Setup(nullptr, nullptr);
     mds_->AddTrigger(MemoryDumpType::PEAK_MEMORY_USAGE,
                      MemoryDumpLevelOfDetail::LIGHT, kMinPollsToDump);
-    mds_->polling_state_.ResetTotals();
-    mds_->polling_state_.current_state =
+    mds_->polling_state_->ResetTotals();
+    mds_->polling_state_->current_state =
         MemoryDumpScheduler::PollingTriggerState::ENABLED;
   }
 
   void TearDown() override {
-    mds_->polling_state_.current_state =
+    mds_->polling_state_->current_state =
         MemoryDumpScheduler::PollingTriggerState::DISABLED;
-    mds_.reset();
   }
 
  protected:
@@ -44,7 +44,7 @@ class MemoryDumpSchedulerPollingTest : public testing::Test {
   }
 
   uint32_t num_samples_tracked_;
-  std::unique_ptr<MemoryDumpScheduler> mds_;
+  MemoryDumpScheduler* mds_;
 };
 
 TEST_F(MemoryDumpSchedulerPollingTest, PeakDetection) {