Merge "Add null check before detach content view from dragView at onDropComplete" into sc-dev am: 5b786ca88d

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/15042822

Change-Id: Idc12dd2613200ce6e9901856b14c4ce0c5946fb6