Merge "Apply theme color and fade-in transition effect at the top of One-handed mode" into sc-dev am: a08d1cb0 am: 9d1f0094 am: 587d389d

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/15234619

Change-Id: I2abe413eb6609c58b8787e1b63d798ea8c6fe197