Remove Key.isStick, use backgroundType="stick" instead

Change-Id: I50e88c0870a3fe360b81f19163ca2f64ec38d8e8
diff --git a/java/res/values/attrs.xml b/java/res/values/attrs.xml
index 0451c9f..6e9461a 100644
--- a/java/res/values/attrs.xml
+++ b/java/res/values/attrs.xml
@@ -199,9 +199,8 @@
             <enum name="normal" value="0" />
             <enum name="functional" value="1" />
             <enum name="action" value="2" />
+            <enum name="sticky" value="3" />
         </attr>
-        <!-- Whether this is a toggle key. -->
-        <attr name="isSticky" format="boolean" />
         <!-- Whether long-pressing on this key will make it repeat. -->
         <attr name="isRepeatable" format="boolean" />
         <!-- The string of characters to output when this key is pressed. -->
diff --git a/java/res/xml-sw600dp/kbd_key_styles.xml b/java/res/xml-sw600dp/kbd_key_styles.xml
index d86a01d..0b6d871 100644
--- a/java/res/xml-sw600dp/kbd_key_styles.xml
+++ b/java/res/xml-sw600dp/kbd_key_styles.xml
@@ -44,8 +44,7 @@
         latin:code="@integer/key_shift"
         latin:keyIcon="iconShiftKey"
         latin:keyIconShifted="iconShiftedShiftKey"
-        latin:backgroundType="functional"
-        latin:isSticky="true" />
+        latin:backgroundType="sticky" />
     <key-style
         latin:styleName="deleteKeyStyle"
         latin:code="@integer/key_delete"
diff --git a/java/res/xml-sw768dp/kbd_key_styles.xml b/java/res/xml-sw768dp/kbd_key_styles.xml
index 4deb263..686e7b6 100644
--- a/java/res/xml-sw768dp/kbd_key_styles.xml
+++ b/java/res/xml-sw768dp/kbd_key_styles.xml
@@ -26,8 +26,7 @@
         latin:code="@integer/key_shift"
         latin:keyIcon="iconShiftKey"
         latin:keyIconShifted="iconShiftedShiftKey"
-        latin:backgroundType="functional"
-        latin:isSticky="true" />
+        latin:backgroundType="sticky" />
     <key-style
         latin:styleName="deleteKeyStyle"
         latin:code="@integer/key_delete"
diff --git a/java/res/xml/kbd_key_styles.xml b/java/res/xml/kbd_key_styles.xml
index 9ed97b1..11b1abb 100644
--- a/java/res/xml/kbd_key_styles.xml
+++ b/java/res/xml/kbd_key_styles.xml
@@ -67,8 +67,7 @@
         latin:code="@integer/key_shift"
         latin:keyIcon="iconShiftKey"
         latin:keyIconShifted="iconShiftedShiftKey"
-        latin:backgroundType="functional"
-        latin:isSticky="true" />
+        latin:backgroundType="sticky" />
     <key-style
         latin:styleName="deleteKeyStyle"
         latin:code="@integer/key_delete"