Add a canSplitKeyboard attribute for specifying split keyboard layouts

Change [1/3]

This'll be used in conjunction with a user preference to split the keyboard when possible.

Bug: 4968173
Change-Id: I7a05948d67b94a55024790115ae261d7fef7941a
diff --git a/java/res/values/attrs.xml b/java/res/values/attrs.xml
index f1253b4..c5c6326 100644
--- a/java/res/values/attrs.xml
+++ b/java/res/values/attrs.xml
@@ -514,6 +514,8 @@
         <attr name="elementKeyboard" format="reference"/>
         <!-- Enable proximity characters correction. Disabled by default. -->
         <attr name="enableProximityCharsCorrection" format="boolean" />
+        <!-- Indicates if the keyboard layout supports being split or not. false by default -->
+        <attr name="supportsSplitLayout" format="boolean" />
     </declare-styleable>
 
     <declare-styleable name="KeyboardLayoutSet_Feature">
diff --git a/java/res/xml/keyboard_layout_set_qwerty.xml b/java/res/xml/keyboard_layout_set_qwerty.xml
index 8215170..1aa6f01 100644
--- a/java/res/xml/keyboard_layout_set_qwerty.xml
+++ b/java/res/xml/keyboard_layout_set_qwerty.xml
@@ -23,7 +23,8 @@
     <Element
         latin:elementName="alphabet"
         latin:elementKeyboard="@xml/kbd_qwerty"
-        latin:enableProximityCharsCorrection="true" />
+        latin:enableProximityCharsCorrection="true"
+        latin:supportsSplitLayout="false" />
     <Element
         latin:elementName="symbols"
         latin:elementKeyboard="@xml/kbd_symbols" />