Remove memory_pressure component.

components/memory_pressure/memory_pressure_stats_collector.h

-// 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.
-
-#ifndef COMPONENTS_MEMORY_PRESSURE_MEMORY_PRESSURE_STATS_COLLECTOR_H_
-#define COMPONENTS_MEMORY_PRESSURE_MEMORY_PRESSURE_STATS_COLLECTOR_H_
-
-#include "base/macros.h"
-#include "base/time/time.h"
-#include "components/memory_pressure/memory_pressure_listener.h"
-
-namespace base {
-class TickClock;
-}
-
-namespace memory_pressure {
-
-// Enumeration of UMA memory pressure levels. The pressure level enum defined in
-// MemoryPressureListener is non-contiguous. This enum is a contiguous version
-// of that for use with UMA. Both it and histograms.xml must be kept in sync
-// with the MemoryPressureListener enum. Included in the header so that
-// UMA_MEMORY_PRESSURE_LEVEL_COUNT is available.
-enum MemoryPressureLevelUMA {
-  UMA_MEMORY_PRESSURE_LEVEL_NONE = 0,
-  UMA_MEMORY_PRESSURE_LEVEL_MODERATE = 1,
-  UMA_MEMORY_PRESSURE_LEVEL_CRITICAL = 2,
-  // This must be the last value in the enum.
-  UMA_MEMORY_PRESSURE_LEVEL_COUNT,
-};
-
-// Enumeration of UMA pressure level changes. This needs to be kept in sync
-// with histograms.xml and the memory pressure levels defined in
-// MemoryPressureListener. Exposed for unittesting.
-enum MemoryPressureLevelChangeUMA {
-  UMA_MEMORY_PRESSURE_LEVEL_CHANGE_NONE_TO_MODERATE = 0,
-  UMA_MEMORY_PRESSURE_LEVEL_CHANGE_NONE_TO_CRITICAL = 1,
-  UMA_MEMORY_PRESSURE_LEVEL_CHANGE_MODERATE_TO_CRITICAL = 2,
-  UMA_MEMORY_PRESSURE_LEVEL_CHANGE_CRITICAL_TO_MODERATE = 3,
-  UMA_MEMORY_PRESSURE_LEVEL_CHANGE_CRITICAL_TO_NONE = 4,
-  UMA_MEMORY_PRESSURE_LEVEL_CHANGE_MODERATE_TO_NONE = 5,
-  // This must be the last value in the enum.
-  UMA_MEMORY_PRESSURE_LEVEL_CHANGE_COUNT
-};
-
-// Class that is responsible for collecting and eventually reporting memory
-// pressure statistics. Contributes to the "Memory.PressureLevel" and
-// "Memory.PressureLevelChanges" histograms.
-//
-// On platforms with a polling memory pressure implementation the
-// UpdateStatistics function will be invoked every time the pressure is polled.
-// On non-polling platforms (Mac, Android) it will be invoked on a periodic
-// timer, and at the moment of pressure level changes.
-class MemoryPressureStatsCollector {
- public:
-  using MemoryPressureLevel = MemoryPressureListener::MemoryPressureLevel;
-
-  // The provided |tick_clock| must outlive this class.
-  MemoryPressureStatsCollector(base::TickClock* tick_clock);
-
-  // This is to be called periodically to ensure that up to date statistics
-  // have been reported.
-  void UpdateStatistics(MemoryPressureLevel current_pressure_level);
-
- private:
-  friend class TestMemoryPressureStatsCollector;
-
-  // Helper functions for delivering collected statistics.
-  static void ReportCumulativeTime(MemoryPressureLevel pressure_level,
-                                   int seconds);
-  static void ReportLevelChange(MemoryPressureLevel old_pressure_level,
-                                MemoryPressureLevel new_pressure_level);
-
-  // The tick clock in use. This class is intended to be owned by a class with
-  // a tick clock, and ownership remains there. Also intended as a test seam.
-  base::TickClock* tick_clock_;
-
-  // Buckets of time that have been spent in different pressure levels, but
-  // not yet reported. At every call to UpdateStatistics these buckets will be
-  // drained of as many 'full' seconds of time as possible and reported via
-  // UMA. The remaining time (< 1000 ms) will be left in the bucket to be rolled
-  // into a later UMA report.
-  base::TimeDelta unreported_cumulative_time_[UMA_MEMORY_PRESSURE_LEVEL_COUNT];
-
-  // The last observed pressure level and the time at which it was observed, and
-  // the time when this pressure level started.
-  MemoryPressureLevel last_pressure_level_;
-  base::TimeTicks last_update_time_;
-
-  DISALLOW_COPY_AND_ASSIGN(MemoryPressureStatsCollector);
-};
-
-}  // namespace memory_pressure
-
-#endif  // COMPONENTS_MEMORY_PRESSURE_MEMORY_PRESSURE_STATS_COLLECTOR_H_