Move phrase gesture from additional features to public.

Bug: 15758242
Change-Id: I703dc2703afdf9402c5d2ac27411b74ece993dba
diff --git a/java/res/xml/prefs.xml b/java/res/xml/prefs.xml
index e71d951..550e71a 100644
--- a/java/res/xml/prefs.xml
+++ b/java/res/xml/prefs.xml
@@ -103,6 +103,13 @@
             android:title="@string/gesture_preview_trail"
             android:defaultValue="true"
             android:persistent="true" />
+        <CheckBoxPreference
+            android:key="pref_gesture_space_aware"
+            android:dependency="gesture_input"
+            android:title="@string/gesture_space_aware"
+            android:summary="@string/gesture_space_aware_summary"
+            android:defaultValue="true"
+            android:persistent="true" />
     </PreferenceScreen>
     <PreferenceScreen
         android:title="@string/settings_screen_correction"