Let each display have one status bar and one navigation bar. This is
so on each display, status bar and navigation bar can be laid out with
apps and produce proper insets.
Bug: 117474929
Test: atest com.android.server.wm
Test: Watch YouTube video in fullscreen mode, and see if status bar
and navigation will be hidden as expected. Swipe on the edge
of screen and see if status bar and navigation bar are both
shown as expected.
Change-Id: I1550659b7cd1dd1676bf04483c5b68376ef42905
7c610aaab3