Respect always unlocked displays when keyguard is shown.

When keyguard is shown on the default display, all secondary displays
report mHasContent=false, even if these displays are created with
FLAG_ALWAYS_UNLOCKED (in practice this means that these displays
belong to an always unlocked virtual device).

Setting mHasContent=false on such displays is wrong - any windows
there are visible and interactive. This also does not propagate
display changes to these windows, which causes a bug when the display
is rotated.

Fix: 285141170
Test: m
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:1df55100cf2546c257b3722531a4668d193d3a1e)
Merged-In: Ief1fa2db10c234ba179ba741434ce3d6ebef290e
Change-Id: Ief1fa2db10c234ba179ba741434ce3d6ebef290e