Dispatch newDisplayLayout in updateDisplayLayout() directly

Empty DisplayLayout do not contain navigation bar height

Bug : Cold boot and set 3 Button NavBar Mode, observe
one handed mode can not trigger

Recovery step : Rotate once and the gesture become activate

Fixes: 183951120
Test: create forest and flash ROM, set NavBar 3 Button Mode.
Test: atest WMShellUnitTests
Change-Id: I930216719f77d0e15d46790e02b788ce9cd80e98