Using the new MemoryPressureListener instead of the LowMemoryObserver when the enhanced memory mana…

base/chromeos/memory_pressure_observer_chromeos.h

Index: base/chromeos/memory_pressure_observer_chromeos.h
diff --git a/base/chromeos/memory_pressure_observer_chromeos.h b/base/chromeos/memory_pressure_observer_chromeos.h
index 445119efb73853c1f712dab8c85ad190ddb86f6b..23b6b3450d8cf2f9ef7f907be1aab144b69ff58f 100644
--- a/base/chromeos/memory_pressure_observer_chromeos.h
+++ b/base/chromeos/memory_pressure_observer_chromeos.h
@@ -6,12 +6,16 @@
 #define BASE_CHROMEOS_MEMORY_PRESSURE_OBSERVER_CHROMEOS_H_
 
 #include "base/base_export.h"
+#include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/memory/memory_pressure_listener.h"
+#include "base/memory/weak_ptr.h"
 #include "base/timer/timer.h"
 
 namespace base {
 
+class TestMemoryPressureObserver;
+
 ////////////////////////////////////////////////////////////////////////////////
 // MemoryPressureObserverChromeOS
 //
@@ -21,8 +25,15 @@ namespace base {
 //
 class BASE_EXPORT MemoryPressureObserverChromeOS {
  public:
+  using GetUsedMemoryInPercentCallback = int (*)();
+
   MemoryPressureObserverChromeOS();
-  ~MemoryPressureObserverChromeOS();
+  virtual ~MemoryPressureObserverChromeOS();
+
+  // Redo the memory pressure calculation soon and call again if a critical
+  // memory pressure prevails. Note that this call will trigger an asynchronous
+  // action which gives the system time to release memory back into the pool.
+  void ScheduleEarlyCheck();
 
   // Get the current memory pressure level.
   base::MemoryPressureListener::MemoryPressureLevel GetCurrentPressureLevel() {
@@ -30,6 +41,7 @@ class BASE_EXPORT MemoryPressureObserverChromeOS {
   }
 
  private:
+  friend TestMemoryPressureObserver;
   // Starts observing the memory fill level.
   // Calls to StartObserving should always be matched with calls to
   // StopObserving.
@@ -39,10 +51,14 @@ class BASE_EXPORT MemoryPressureObserverChromeOS {
   // May be safely called if StartObserving has not been called.
   void StopObserving();
 
-  // The function which gets periodically be called to check any changes in the
-  // memory pressure.
+  // The function which gets periodically called to check any changes in the
+  // memory pressure. It will report pressure changes as well as continuous
+  // critical pressure levels.
   void CheckMemoryPressure();
 
+  // Get the memory pressure in percent (virtual for testing).
+  virtual int GetUsedMemoryInPercent();
+
   // The current memory pressure.
   base::MemoryPressureListener::MemoryPressureLevel
       current_memory_pressure_level_;
@@ -51,6 +67,12 @@ class BASE_EXPORT MemoryPressureObserverChromeOS {
   // replaced by a kernel triggered event system (see crbug.com/381196).
   base::RepeatingTimer<MemoryPressureObserverChromeOS> timer_;
 
+  // To slow down the amount of moderate pressure event calls, this counter
+  // gets used to count the number of events since the last event occured.
+  int moderate_pressure_repeat_count_;
+
+  base::WeakPtrFactory<MemoryPressureObserverChromeOS> weak_ptr_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(MemoryPressureObserverChromeOS);
 };