Merge remote-tracking branch 'aosp/pie-gsi' into HEAD

* aosp/pie-gsi:
  DO NOT MERGE Set ContainerLayer for buffer-less surface
  DO NOT MERGE: WM: Restrict SC Builder to set a single surface type
  Implement construction of container layers
  SystemConfig: allow reading sku specific props
  Nullify the default wallpaper component if it does not exist

Change-Id: I9f7bb9a2a4f9035cd680ed27dfb82b624ccabb19