Merge "Fix leakage of DisplayContent referenced from TransitionController" into sc-v2-dev am: c89faed0bd am: f779323d35

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/16660805

Change-Id: I0f3ff1c86613fe472dcaa4d95ac1dbae5357ca78