Clear low profile mode while forcing client to show system bars

Forcing client to show system bars would clear system UI flags at the
client side. SYSTEM_UI_FLAG_LOW_PROFILE would be cleared as well in
previous Android versions. This CL makes the behavior compatible.

Fix: 167892531
Test: Steps in the bug
Change-Id: I466a05120a08ac95b619eadd8291fc546d3bb450