Make Spacer as extended Key class

Bug: 5275003
Change-Id: I809a8ca363ba72b22ac5cfd926414990f7e8467c
diff --git a/java/res/values/attrs.xml b/java/res/values/attrs.xml
index 3d6428d..a456b22 100644
--- a/java/res/values/attrs.xml
+++ b/java/res/values/attrs.xml
@@ -150,8 +150,8 @@
              area between the nearest key on the left hand side and the right edge of the keyboard.
              -->
         <attr name="keyWidth" format="dimension|fraction|enum">
-            <enum name="fillRight" value="0" />
-            <enum name="fillBoth" value="-1" />
+            <enum name="fillRight" value="-1" />
+            <enum name="fillBoth" value="-2" />
         </attr>
         <!-- Default height of a row (key height + vertical gap), in pixels or percentage of
              keyboard height. -->