memory-infra: Switch to MemoryPeakDetector and simplify MemoryDumpScheduler

base/trace_event/memory_peak_detector_unittest.cc

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/trace_event/memory_peak_detector.h"
 
 #include <memory>
 
 #include "base/bind.h"
 #include "base/logging.h"
@@ skipping 66 matching lines @@
 
   void SetUp() override {
     get_mdp_call_count_ = 0;
     RestartThreadAndReinitializePeakDetector();
   }
 
   void TearDown() override {
     peak_detector_->TearDown();
     bg_thread_->FlushForTesting();
     EXPECT_EQ(MemoryPeakDetector::NOT_INITIALIZED, GetPeakDetectorState());
+    bg_thread_.reset();
     dump_providers_.clear();
   }
 
   // Calls MemoryPeakDetector::state_for_testing() on the bg thread and returns
   // the result on the current thread.
   MemoryPeakDetector::State GetPeakDetectorState() {
     WaitableEvent evt(WaitableEvent::ResetPolicy::MANUAL,
                       WaitableEvent::InitialState::NOT_SIGNALED);
     MemoryPeakDetector::State res = MemoryPeakDetector::NOT_INITIALIZED;
     auto get_fn = [](MemoryPeakDetector* peak_detector, WaitableEvent* evt,
@@ skipping 422 matching lines @@
           peak_detector->Clear();
         return PollFunctionThatCausesPeakViaStdDev(sample_idx);
       },
       Unretained(&*peak_detector_));
   uint32_t num_peaks = RunWithCustomPollFunction(kConfig, kNumSamples, poll_fn);
   EXPECT_EQ(0u, num_peaks);
 }
 
 }  // namespace trace_event
 }  // namespace base