Clear all DragView in onResume

- Multiple users reports view getting stuck on screen. This CL
  clears all DragView when user leaves launcher.
- Moved to onResume to not interfere with start up time,
  and also aligned with when we remove AbstractFloatingView.
- Root cause still undetermined, but happens enough that it warrants
  a temp fix.

Bug: 162636845
Test: drag and drop configurable widget
      (widget that gets dropped then opens up a
       configuration activity)
Change-Id: I532b5274a1308c53f67c23c5c8ca07f2b7f9802c
diff --git a/src/com/android/launcher3/Launcher.java b/src/com/android/launcher3/Launcher.java
index ad87451..135b88d 100644
--- a/src/com/android/launcher3/Launcher.java
+++ b/src/com/android/launcher3/Launcher.java
@@ -1169,6 +1169,7 @@
         }
 
         AbstractFloatingView.closeAllOpenViewsExcept(this, false, TYPE_REBIND_SAFE);
+        DragView.removeAllViews(this);
         TraceHelper.INSTANCE.endSection(traceToken);
     }