Map STATE_VR to STATE_ON for Battery Stats.

Also, sets STATE_VR to be a public API value for Android O release.

Test: Switch to VR mode, ensure "Unexpected screen state: 5" no
longer logs from BatteryStatsImpl
Bug: 35636815

Change-Id: I1f8be334967e1af1f92a3ed571c063e7b00106b1
diff --git a/core/java/android/os/BatteryStats.java b/core/java/android/os/BatteryStats.java
index 013972d..763072f 100644
--- a/core/java/android/os/BatteryStats.java
+++ b/core/java/android/os/BatteryStats.java
@@ -2406,6 +2406,10 @@
     // Step duration mode: the screen is on, off, dozed, etc; value is Display.STATE_* - 1.
     public static final int STEP_LEVEL_MODE_SCREEN_STATE = 0x03;
 
+    // The largest value for screen state that is tracked in battery states. Any values above
+    // this should be mapped back to one of the tracked values before being tracked here.
+    public static final int MAX_TRACKED_SCREEN_STATE = Display.STATE_DOZE_SUSPEND;
+
     // Step duration mode: power save is on.
     public static final int STEP_LEVEL_MODE_POWER_SAVE = 0x04;