Make memory pressure notifier configurable

base/memory/memory_pressure_monitor_win.cc

Index: base/memory/memory_pressure_monitor_win.cc
diff --git a/base/memory/memory_pressure_monitor_win.cc b/base/memory/memory_pressure_monitor_win.cc
index 8ac66cec0880248cdea7107cd2c6b33806e4cdf4..2bb8cd0c27cae882a74da0e4e824d6e1ac70cece 100644
--- a/base/memory/memory_pressure_monitor_win.cc
+++ b/base/memory/memory_pressure_monitor_win.cc
@@ -198,7 +198,7 @@ void MemoryPressureMonitor::CheckMemoryPressure() {
   // happen for moderate and critical pressure levels.
   DCHECK_NE(MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE,
             current_memory_pressure_level_);
-  MemoryPressureListener::NotifyMemoryPressure(current_memory_pressure_level_);
+  dispatch_callback_(current_memory_pressure_level_);
 }
 
 void MemoryPressureMonitor::CheckMemoryPressureAndRecordStatistics() {
@@ -250,5 +250,9 @@ bool MemoryPressureMonitor::GetSystemMemoryStatus(
   return true;
 }
 
+void MemoryPressureMonitor::SetDispatchCallback(DispatchCallback callback) {
+  dispatch_callback_ = callback;
+}
+
 }  // namespace win
 }  // namespace base