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: Ib55c3525909d6a4b4e4123c9197c364147e3639f