Preventing concurrentmodification exception when dragging a icon

with shortcuts from inside a folder

When dragging the icon, DeepShortcutContainer removes itself as a
dragListener causing the exception

Change-Id: Ifb2b4a3045caa54aa0b6a9b525055ffdcfaa04a6

src/com/android/launcher3/dragndrop/DragController.java

@@ -260,7 +260,7 @@ public class DragController implements DragDriver.EventListener, TouchController
         dragView.show(mMotionDownX, mMotionDownY);
         mDistanceSinceScroll = 0;
 
-        for (DragListener listener : mListeners) {
+        for (DragListener listener : new ArrayList<>(mListeners)) {
             listener.onDragStart(mDragObject, mOptions);
         }