Merge "Add TransitionController to member of WindowContainer" into sc-v2-dev am: 9b9cca942e am: 033da32f9b

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/15937039

Change-Id: Iada1f954db78923c71f2eaee929720cdf147f13e