Allow navigation bar drawing during window animations

Bug: 22605259
Change-Id: I080dc7bf2dfdc6666a5f38eebecc7c9a6034d04a

packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarView.java

@@ -40,6 +40,7 @@ import android.view.MotionEvent;
 import android.view.Surface;
 import android.view.View;
 import android.view.ViewGroup;
+import android.view.ViewRootImpl;
 import android.view.WindowManager;
 import android.view.inputmethod.InputMethodManager;
 import android.widget.FrameLayout;
@@ -184,6 +185,15 @@ public class NavigationBarView extends LinearLayout {
         mBarTransitions = new NavigationBarTransitions(this);
     }
 
+    @Override
+    protected void onAttachedToWindow() {
+        super.onAttachedToWindow();
+        ViewRootImpl root = getViewRootImpl();
+        if (root != null) {
+            root.setDrawDuringWindowsAnimating(true);
+        }
+    }
+
     public BarTransitions getBarTransitions() {
         return mBarTransitions;
     }