Framework change for #2583442: Navigation dies when night mode changes

The window manager doesn't retain its keep screen on lock while
in the process of destroying and creating new activity windows during
a config change.  Now it does.

Unfortunately, this doesn't help maps, since it doesn't use our
lovely KEEP_SCREEN_ON flag. :p

Change-Id: Ida4bc0fcfe132cdff2bd4eeb7ba0ce9731504d14