Don't re-animate volume dialog dismissal

- If the VolumeDialog is already dismissing, don't
restart its dismissing animation

Test: manual
Bug: 112347302
Change-Id: I588d0662ee2948ae5cfd52ee5989c473942bf2a0
diff --git a/packages/SystemUI/src/com/android/systemui/volume/VolumeDialogImpl.java b/packages/SystemUI/src/com/android/systemui/volume/VolumeDialogImpl.java
index 02babac..13c43f7 100644
--- a/packages/SystemUI/src/com/android/systemui/volume/VolumeDialogImpl.java
+++ b/packages/SystemUI/src/com/android/systemui/volume/VolumeDialogImpl.java
@@ -1195,7 +1195,7 @@
 
         @Override
         public boolean onTouchEvent(MotionEvent event) {
-            if (isShowing()) {
+            if (mShowing) {
                 if (event.getAction() == MotionEvent.ACTION_OUTSIDE) {
                     dismissH(Events.DISMISS_REASON_TOUCH_OUTSIDE);
                     return true;