Make memory pressure notifier configurable

chromecast/browser/cast_memory_pressure_monitor.cc

Index: chromecast/browser/cast_memory_pressure_monitor.cc
diff --git a/chromecast/browser/cast_memory_pressure_monitor.cc b/chromecast/browser/cast_memory_pressure_monitor.cc
index 75d8d0e6b4bdc1c97e3c69f4f561dafa59c1efe3..2ec92711e312950522680de3d82cf4f68e8891f1 100644
--- a/chromecast/browser/cast_memory_pressure_monitor.cc
+++ b/chromecast/browser/cast_memory_pressure_monitor.cc
@@ -111,7 +111,7 @@ void CastMemoryPressureMonitor::PollPressureLevel() {
 void CastMemoryPressureMonitor::UpdateMemoryPressureLevel(
     MemoryPressureLevel new_level) {
   if (new_level != base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE)
-    base::MemoryPressureListener::NotifyMemoryPressure(new_level);
+    Notify(new_level);
 
   if (new_level == current_level_)
     return;
@@ -121,4 +121,18 @@ void CastMemoryPressureMonitor::UpdateMemoryPressureLevel(
       "Memory.Pressure.LevelChange", new_level);
 }
 
+void CastMemoryPressureMonitor::SetObserver(
+    base::MemoryPressureMonitorObserver* observer) {
+  DCHECK(!observer_);
+  observer_ = observer;
+}
+
+void CastMemoryPressureMonitor::Notify(MemoryPressureLevel level) {
+  if (observer_) {
+    observer_->OnMemoryPressure(level);
+  } else {
+    base::MemoryPressureListener::NotifyMemoryPressure(level);
+  }
+}
+
 }  // namespace chromecast