Merge "Remove dividers when expanding groups." into sc-dev am: 5f1b2bdd am:...

Merge "Remove dividers when expanding groups." into sc-dev am: 5f1b2bdd am: b0f3c9d7 am: 5b2b8bf1

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/15013931

Change-Id: I5e894e980c2d4aa6959da5e397b742d874fa5000