Hide swipe-up gesture behind tuner flag

(;゚︵゚;)

Bug: 26317834
Change-Id: If489d2bac21e376f2b24a3ce0537a2a8a29651ab
diff --git a/packages/SystemUI/res/values/strings.xml b/packages/SystemUI/res/values/strings.xml
index 76752e6..6ff9be1 100644
--- a/packages/SystemUI/res/values/strings.xml
+++ b/packages/SystemUI/res/values/strings.xml
@@ -1184,6 +1184,11 @@
     <!-- Description for the toggle to set the initial scroll state to be paging or stack. DO NOT TRANSLATE -->
     <string name="overview_initial_state_paging_desc">Determines whether Overview will initially be in a stacked or paged state</string>
 
+    <!-- Toggle to enable the gesture to enter split-screen by swiping up from the Overview button. [CHAR LIMIT=60]-->
+    <string name="overview_nav_bar_gesture">Enable split-screen swipe-up accelerator</string>
+    <!-- Description for the toggle to enable the gesture to enter split-screen by swiping up from the Overview button. [CHAR LIMIT=NONE]-->
+    <string name="overview_nav_bar_gesture_desc">Enable gesture to enter split-screen by swiping up from the Overview button</string>
+
     <!-- Category in the System UI Tuner settings, where new/experimental
          settings are -->
     <string name="experimental">Experimental</string>
diff --git a/packages/SystemUI/res/xml/tuner_prefs.xml b/packages/SystemUI/res/xml/tuner_prefs.xml
index febe518..4de4ced 100644
--- a/packages/SystemUI/res/xml/tuner_prefs.xml
+++ b/packages/SystemUI/res/xml/tuner_prefs.xml
@@ -122,6 +122,11 @@
             android:title="@string/overview_fast_toggle_via_button"
             android:summary="@string/overview_fast_toggle_via_button_desc" />
 
+        <com.android.systemui.tuner.TunerSwitch
+            android:key="overview_nav_bar_gesture"
+            android:title="@string/overview_nav_bar_gesture"
+            android:summary="@string/overview_nav_bar_gesture_desc" />
+
     </PreferenceScreen>
 
     <SwitchPreference
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarGestureHelper.java b/packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarGestureHelper.java
index a2586f1..bb03454 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarGestureHelper.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarGestureHelper.java
@@ -304,8 +304,7 @@
     public void onTuningChanged(String key, String newValue) {
         switch (key) {
             case KEY_DOCK_WINDOW_GESTURE:
-                mDockWindowEnabled = (newValue == null) ||
-                        (Integer.parseInt(newValue) != 0);
+                mDockWindowEnabled = newValue != null && (Integer.parseInt(newValue) != 0);
                 break;
         }
     }