Use Signal Callback in Ambient Light Sensor

ambient_light_sensor.h

Index: ambient_light_sensor.h
diff --git a/ambient_light_sensor.h b/ambient_light_sensor.h
index 0442a831f28a90d653913d674f3a0478e85b28a0..49edab0af76db86e0dc32b718170c27ee8edca46 100644
--- a/ambient_light_sensor.h
+++ b/ambient_light_sensor.h
@@ -8,6 +8,7 @@
 #include <glib.h>
 
 #include "power_manager/backlight_controller.h"
+#include "power_manager/signal_callback.h"
 
 namespace power_manager {
 
@@ -47,8 +48,8 @@ class AmbientLightSensor {
   void EnableOrDisableSensor(PowerState power, DimState dim);
 
  private:
-  static gboolean ReadAls(gpointer data);
-  static bool DeferredInit(AmbientLightSensor* self);
+  SIGNAL_CALLBACK_0(AmbientLightSensor, gboolean, ReadAls);
+  bool DeferredInit();
 
   // Return a luma level normalized to 100 based on the tsl2563 lux value.
   // The luma level will modify the controller's brightness calculation.