Merge "Initial commit of rotation contextual button." into sc-v2-dev am: 161027dc3e am: 3b381a35f7

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/14726215

Change-Id: I3f310278af13f9a72f74b4d6206744f4aa031157