healthd: Add callback for screen_on to the healthdHAL

Adds a callback to the healthdHAL which can check for device specific
properties to decide if the screen should turn on.

Change-Id: I543e7729ecb291157df4d3be1bd718f8af01ac40
Signed-off-by: Ruchi Kandoi<kandoiruchi@google.com>
diff --git a/healthd/healthd.h b/healthd/healthd.h
index 972e728..4704f0b 100644
--- a/healthd/healthd.h
+++ b/healthd/healthd.h
@@ -67,6 +67,7 @@
     android::String8 batteryChargeCounterPath;
 
     int (*energyCounter)(int64_t *);
+    bool (*screen_on)(android::BatteryProperties *props);
 };
 
 // Global helper functions