Merge "Add ContrastDialog class and tests, activity version" into udc-dev am: 8138fa29

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/22411301



Change-Id: Ic98ee0ebebe7ffdc9c2b3ae9d7901c359bf66c60
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>