Add isScreenOn() to LocalPowerManager interface so we can call it from PhoneWindowManager

Needed for the fix for b/2260437 (device wakes itself back up when camera is last application running)

Change-Id: I0e419fcf05542df203eb3f127dde7a888416e86d
Signed-off-by: Mike Lockwood <lockwood@android.com>
diff --git a/core/java/android/os/LocalPowerManager.java b/core/java/android/os/LocalPowerManager.java
index 2c6b29a..3fe21d9 100644
--- a/core/java/android/os/LocalPowerManager.java
+++ b/core/java/android/os/LocalPowerManager.java
@@ -45,4 +45,6 @@
 
     // the same as the method on PowerManager
     public void userActivity(long time, boolean noChangeLights, int eventType);
+
+    boolean isScreenOn();
 }