camera3: Add camera neutral tag.

Change-Id: Ia7e8c444256ce2a587ce708c2e6e951dec9bbdc8
diff --git a/core/java/android/hardware/camera2/CaptureResult.java b/core/java/android/hardware/camera2/CaptureResult.java
index 160b6fc..543ce21 100644
--- a/core/java/android/hardware/camera2/CaptureResult.java
+++ b/core/java/android/hardware/camera2/CaptureResult.java
@@ -1440,6 +1440,16 @@
             new Key<Float>("android.sensor.temperature", float.class);
 
     /**
+     * <p>The estimated white balance at the time of capture.</p>
+     * <p>The estimated white balance encoded as the RGB values of the
+     * perfectly neutral color point in the linear native sensor color space.
+     * The order of the values is R, G, B; where R is in the lowest index.</p>
+     * <p><b>Optional</b> - This value may be {@code null} on some devices.</p>
+     */
+    public static final Key<Rational[]> SENSOR_NEUTRAL_COLOR_POINT =
+            new Key<Rational[]>("android.sensor.neutralColorPoint", Rational[].class);
+
+    /**
      * <p>When enabled, the sensor sends a test pattern instead of
      * doing a real exposure from the camera.</p>
      * <p>When a test pattern is enabled, all manual sensor controls specified