Merge "Show correct last notification time for grouped notifications" into...

Merge "Show correct last notification time for grouped notifications" into udc-dev am: f32a80bf am: 3b85b3a3

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/21609427



Change-Id: Icd7000d5d1fc35439734f5668e4f5329c1917024
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>