Merge "[flexiglass] Fixes back navigation." into udc-qpr-dev am: 3c0f4149 am: 5e1aaad4

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/24152990



Change-Id: I2d0a861289049f32f58331d4eb7625139941b27c
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>