Fixes bug in SurfacesServiceApplication

When a SurfacesImpl is being destroyed it may not contain the active
display. SurfacesServiceApplication should only reset the display if
the SurfacesImpl being destroyed contains the active display.

Without this fix apps like wm_flow don't update at all.

R=jam@chromium.org

Review URL: https://codereview.chromium.org/728483002