Make memory pressure notifier configurable

base/memory/memory_pressure_monitor_chromeos.h

Index: base/memory/memory_pressure_monitor_chromeos.h
diff --git a/base/memory/memory_pressure_monitor_chromeos.h b/base/memory/memory_pressure_monitor_chromeos.h
index 5529c3b48a35857ddb1f923671a8850589354a5a..1000f30098792254a851d562000e53746f042916 100644
--- a/base/memory/memory_pressure_monitor_chromeos.h
+++ b/base/memory/memory_pressure_monitor_chromeos.h
@@ -60,6 +60,7 @@ class BASE_EXPORT MemoryPressureMonitor : public base::MemoryPressureMonitor {
   // Get the current memory pressure level.
   MemoryPressureListener::MemoryPressureLevel GetCurrentPressureLevel() const
       override;
+  void SetDispatchCallback(const DispatchCallback& callback) override;
 
   // Returns a type-casted version of the current memory pressure monitor. A
   // simple wrapper to base::MemoryPressureMonitor::Get.
@@ -107,6 +108,8 @@ class BASE_EXPORT MemoryPressureMonitor : public base::MemoryPressureMonitor {
   // File descriptor used to detect low memory condition.
   ScopedFD low_mem_file_;
 
+  DispatchCallback dispatch_callback_;
+
   base::WeakPtrFactory<MemoryPressureMonitor> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(MemoryPressureMonitor);