Add a mechanism to adjust auto-brightness at night.

Uses the twilight service to determine the hours of
sunrise and sunset.  Shortly after sunset or before sunrise
gradually start to apply a gamma correction factor to the
auto-brightness calculations to make the screen a little
dimmer at night.

The effect is relatively small and is mostly noticeable
in dark rooms.  This is just a first pass at the algorithm,
we can tweak the adjustment later to ensure that it has even less
impact in moderate or bright environments.

Change-Id: Idf89022a5d0bb52975e04779352d53fa63371178

services/java/com/android/server/SystemServer.java

@@ -741,7 +741,12 @@ class ServerThread extends Thread {
         w.getDefaultDisplay().getMetrics(metrics);
         context.getResources().updateConfiguration(config, metrics);
 
-        power.systemReady();
+        try {
+            power.systemReady(twilight);
+        } catch (Throwable e) {
+            reportWtf("making Power Manager Service ready", e);
+        }
+
         try {
             pm.systemReady();
         } catch (Throwable e) {