Ensure that the decor view is attached to window.

In paticular case, the preserve DecorView object may not attach to window,and
when update the decor view layout params, WMS found that it not attached to
window manager will throw IllegalArgumentException, it will lead app to crash.

Test: activity switch case, multi-window case [work fine]

Change-Id: I52c64ac76c8a84b95e5e105fa586628a8284932b