Merge changes from topic "int32ref"

* changes:
  [Mainline] android.system package APIs migration
  Use public android.system.Int64Ref instead of Int32Ref which is hidden (CorePlatformApi) type of libcore
tree: 2630f99103c959812a88b5a8387da53a4871c33e
  1. core/
  2. framework/
  3. service/
  4. services/
  5. tests/
  6. OWNERS