Fix messed-up divider position when unlocking with IME showing

Bug was happening because we didn't account for the case where the device is unlocked with the IME showing. So the layout was properly being adjusted for IME, but the divider showing animation (applyDividerVisibility) was erroneously setting the divider's position back to the center of the screen afterwards.

Solution is for applyDividerVisibility() to update the full layout using updateSurfaceBounds() instead of just setting the position based on app bounds.

Fixes: 378620695
Flag: EXEMPT bugfix
Test: Bug no longer repros
Change-Id: Ieb7be52a015099addf8fff94edf693b198dfcd17