Revert "Revert "1/ Add onStartTransition() callback for SYSUI_ST..."

Revert submission 14315426-revert_fix_ohm_exit_flicker

Reason for revert: The root cause of b/186197537 is ag/14296935
I should safe to re-landing the 2 CLs

Reverted Changes: 
Ifd17094f0:Revert "1/ Add onStartTransition() callback for SY...
Ia921d073c:Revert "2/ Resolve gesture one handed conflicts sw...

Change-Id: Ieccadf78ab873e00efa5102348c3787f00bd3275