WIP: memory coordinator: Check /dev/chromeos-low-mem to determine memory condition

base/memory/memory_pressure_monitor_chromeos.h

 // Copyright 2014 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 BASE_MEMORY_MEMORY_PRESSURE_MONITOR_CHROMEOS_H_
 #define BASE_MEMORY_MEMORY_PRESSURE_MONITOR_CHROMEOS_H_
 
 #include "base/base_export.h"
-#include "base/files/scoped_file.h"
 #include "base/macros.h"
+#include "base/memory/low_memory_observer_chromeos.h"
 #include "base/memory/memory_pressure_listener.h"
 #include "base/memory/memory_pressure_monitor.h"
 #include "base/memory/weak_ptr.h"
 #include "base/timer/timer.h"
 
 namespace base {
 namespace chromeos {
 
 class TestMemoryPressureMonitor;
 
@@ skipping 84 matching lines @@
   // 5 seconds, but the timer to report "ChromeOS.MemoryPressureLevel"
   // fires every second. This counter is used to allow reporting
   // "Memory.PressureLevel" correctly without adding another
   // timer.
   int seconds_since_reporting_;
 
   // The thresholds for moderate and critical pressure.
   const int moderate_pressure_threshold_percent_;
   const int critical_pressure_threshold_percent_;
 
-  // File descriptor used to detect low memory condition.
-  ScopedFD low_mem_file_;
+  // To detect low memory condition.
+  std::unique_ptr<LowMemoryObserver> low_mem_observer_;
 
   DispatchCallback dispatch_callback_;
 
   base::WeakPtrFactory<MemoryPressureMonitor> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(MemoryPressureMonitor);
 };
 
 }  // namespace chromeos
 }  // namespace base
 
 #endif  // BASE_MEMORY_MEMORY_PRESSURE_MONITOR_CHROMEOS_H_