Fix longpress handler in notifications.

Bug: 6452142
Change-Id: Iaa8e189cd1536f2826d5fe3721ead9bc33397711

Author: dsandler

packages/SystemUI/src/com/android/systemui/SwipeHelper.java

@@ -186,6 +186,7 @@ public static void invalidateGlobalRegion(View view, RectF childBounds) {
     public void removeLongPressCallback() {
         if (mWatchLongPress != null) {
             mHandler.removeCallbacks(mWatchLongPress);
+            mWatchLongPress = null;
         }
     }
 
@@ -245,6 +246,7 @@ public void run() {
                 mCurrView = null;
                 mCurrAnimView = null;
                 mLongPressSent = false;
+                removeLongPressCallback();
                 break;
         }
         return mDragging;