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: I837c61ddaecacf198ce89be0949e79f29a2c7a3d