[Mac] Report statistics more regularly in Mac memory pressure monitor

base/memory/memory_pressure_monitor.h

Index: base/memory/memory_pressure_monitor.h
diff --git a/base/memory/memory_pressure_monitor.h b/base/memory/memory_pressure_monitor.h
index 033379cdb8d51e08151d8ab36bf610264eac909e..e48244b433c89729587641d8031f6f2525fa8dbf 100644
--- a/base/memory/memory_pressure_monitor.h
+++ b/base/memory/memory_pressure_monitor.h
@@ -35,7 +35,7 @@ class BASE_EXPORT MemoryPressureMonitor {
   static void RecordMemoryPressure(MemoryPressureLevel level, int ticks);
 
   // Returns the currently observed memory pressure.
-  virtual MemoryPressureLevel GetCurrentPressureLevel() const = 0;
+  virtual MemoryPressureLevel GetCurrentPressureLevel() = 0;
 
   // Sets a notification callback. The default callback invokes
   // base::MemoryPressureListener::NotifyMemoryPressure.