Remove unused metric from memory_pressure component.

components/memory_pressure/memory_pressure_stats_collector_unittest.cc

 // Copyright 2015 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 "components/memory_pressure/memory_pressure_stats_collector.h"
 
 #include "base/test/histogram_tester.h"
 #include "base/test/simple_test_tick_clock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace memory_pressure {
 
 namespace {
 
 // Histogram names.
 const char kPressureLevel[] = "Memory.PressureLevel";
-const char kPressureLevelChange[] = "Memory.PressureLevelChange";
 
 }  // namespace
 
 // Test version of the stats collector with a few extra accessors.
 class TestMemoryPressureStatsCollector : public MemoryPressureStatsCollector {
  public:
   TestMemoryPressureStatsCollector(base::TickClock* tick_clock)
       : MemoryPressureStatsCollector(tick_clock) {}
 
   // Accessors.
@@ skipping 46 matching lines @@
 
   base::SimpleTestTickClock tick_clock_;
   TestMemoryPressureStatsCollector collector_;
   base::HistogramTester histograms_;
 };
 
 TEST_F(MemoryPressureStatsCollectorTest, EndToEnd) {
   // Upon construction no statistics should yet have been reported.
   ExpectAccumulated(0, 0, 0);
   ExpectReported(0, 0, 0);
-  histograms_.ExpectTotalCount(kPressureLevelChange, 0);
 
   // A first call should not invoke any reporting functions, but it should
   // modify member variables.
   Tick(500);
   collector_.UpdateStatistics(
       MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE);
   EXPECT_EQ(MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE,
             collector_.last_pressure_level());
   EXPECT_EQ(tick_clock_.NowTicks(), collector_.last_update_time());
   ExpectAccumulated(0, 0, 0);
   ExpectReported(0, 0, 0);
-  histograms_.ExpectTotalCount(kPressureLevelChange, 0);
 
   // A subsequent call with the same pressure level should increment the
   // cumulative time but not make a report, as less than one second of time
   // has been accumulated.
   Tick(500);
   collector_.UpdateStatistics(
       MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE);
   EXPECT_EQ(MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE,
             collector_.last_pressure_level());
   EXPECT_EQ(tick_clock_.NowTicks(), collector_.last_update_time());
   ExpectAccumulated(500, 0, 0);
   ExpectReported(0, 0, 0);
-  histograms_.ExpectTotalCount(kPressureLevelChange, 0);
 
   // Yet another call and this time a report should be made, as one second
   // of time has been accumulated. 500ms should remain unreported.
   Tick(1000);
   collector_.UpdateStatistics(
       MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE);
   EXPECT_EQ(MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE,
             collector_.last_pressure_level());
   EXPECT_EQ(tick_clock_.NowTicks(), collector_.last_update_time());
   ExpectAccumulated(500, 0, 0);
   ExpectReported(1, 0, 0);
-  histograms_.ExpectTotalCount(kPressureLevelChange, 0);
 
   // A subsequent call with a different pressure level should increment the
   // cumulative time and make several reports.
   Tick(2250);
   collector_.UpdateStatistics(
       MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE);
   EXPECT_EQ(MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE,
             collector_.last_pressure_level());
   EXPECT_EQ(tick_clock_.NowTicks(), collector_.last_update_time());
   ExpectAccumulated(500, 250, 0);
   ExpectReported(1, 2, 0);
-  histograms_.ExpectBucketCount(
-      kPressureLevelChange, UMA_MEMORY_PRESSURE_LEVEL_CHANGE_NONE_TO_MODERATE,
-      1);
-  histograms_.ExpectTotalCount(kPressureLevelChange, 1);
 }
 
 }  // namespace memory_pressure