Use splitscreen insets for multiwindow, else use thumbnail insets

This is consistent with what we do for the right/bottom clipped
insets already, and fixes cases where the device insets don't
match the thumbnail insets (e.g. for fullscreen apps).

Bug: 157097544
Change-Id: I25216fef0d804704e7c7bd84316f932767c2f110
2 files changed