Merge "Allow populating left_icon independently of right_icon." into sc-dev am: cd86f384 am: 0ed497e6 am: e7ebbe1e

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/14519486

Change-Id: Ia4d1db412590c688bc86964a35d882f21e5dc840