Introduce autoXScale label option

Bug: 5267649
Change-Id: I7fdcb98c209b7ccf73075ef3a4e758782fe161e3
diff --git a/java/res/values/attrs.xml b/java/res/values/attrs.xml
index a456b22..a876e28 100644
--- a/java/res/values/attrs.xml
+++ b/java/res/values/attrs.xml
@@ -217,6 +217,7 @@
             <flag name="hasHintLabel" value="0x800" />
             <flag name="withIconLeft" value="0x1000" />
             <flag name="withIconRight" value="0x2000" />
+            <flag name="autoXScale" value="0x4000" />
         </attr>
         <!-- The icon to display on the key instead of the label. -->
         <attr name="keyIcon" format="enum">