Make memory pressure notifier configurable

base/memory/memory_pressure_monitor_chromeos.cc

Index: base/memory/memory_pressure_monitor_chromeos.cc
diff --git a/base/memory/memory_pressure_monitor_chromeos.cc b/base/memory/memory_pressure_monitor_chromeos.cc
index 2d0b0a62fc6d7c1dbbb77aa98f06132d5f93a966..5138d01c57605615c27a32d600fe57e143e0e0d5 100644
--- a/base/memory/memory_pressure_monitor_chromeos.cc
+++ b/base/memory/memory_pressure_monitor_chromeos.cc
@@ -113,6 +113,8 @@ MemoryPressureMonitor::MemoryPressureMonitor(
       critical_pressure_threshold_percent_(
           GetCriticalMemoryThresholdInPercent(thresholds)),
       low_mem_file_(HANDLE_EINTR(::open(kLowMemFile, O_RDONLY))),
+      dispatch_callback_(
+          base::Bind(&MemoryPressureListener::NotifyMemoryPressure)),
       weak_ptr_factory_(this) {
   StartObserving();
   LOG_IF(ERROR,
@@ -230,7 +232,7 @@ void MemoryPressureMonitor::CheckMemoryPressure() {
     return;
   }
   moderate_pressure_repeat_count_ = 0;
-  MemoryPressureListener::NotifyMemoryPressure(current_memory_pressure_level_);
+  dispatch_callback_.Run(current_memory_pressure_level_);
 }
 
 // Gets the used ChromeOS memory in percent.
@@ -271,5 +273,10 @@ int MemoryPressureMonitor::GetUsedMemoryInPercent() {
   return percentage;
 }
 
+void MemoryPressureMonitor::SetDispatchCallback(
+    const DispatchCallback& callback) {
+  dispatch_callback_ = callback;
+}
+
 }  // namespace chromeos
 }  // namespace base