Merge "Change AssistManger to use dagger's @Main Handler" into sc-v2-dev am: 65031c3762 am: e87993721e

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/16248700

Change-Id: I30f5c060f18c609fe7ff9c8a606716f53dd5cf14